Above is a 1440AD Deed of the private Fief of Blondel and de l'Eperon which is held directly from the crown through court registration and conge/tresieme fees.

Seigneurs of Fiefs and Feudal Fiefs

Style of Seigneur - As per the The Feudal Dues (Guernsey) Law, 1980 Style of Seigneur of a fief etc. Section 4. The foregoing provisions of this Law shall be without prejudice –

(a) to the right of any person to use, in the case of a male person, the style of Seigneur and, in the case of a female person, the style of Dame, of a fief,

(b) to the feudal relationship between Her Majesty and any person holding an interest in a private fief on or at any time after the commencement of this Law, or to the feudal relationship between any person holding an interest in any fief and any person holding an interest in a dependency of that fief, and

(c) to the right or obligation of any person by virtue of that person holding an interest in any fief which is not a right to which those provisions apply or any obligation correlative thereto.
www.guernseylegalresources.gg/CHttpHandler.ashx?id=71301&p=0

From the Supplement to the Memorial of the Jersey Reform Committee to the Commissioners apppointed by Her Most Gracious Majesty to enquire into the civil, municipal, and ecclesiastical laws of Jersey and for other purposes, 1859, p. 39. The Jersey upper classes appropriate a Guernsey Order in Council, to ensure they are correctly addressed by the lower orders.

³ In the 17th century in Jersey, 'At the top of the tree were the Squirearchy, the Seigneurs.' Numbers then ranged from 100 to 130, perhaps about 600 including family members. 'They expected to be addressed by the name of their fiefs, Monsieur des Saumarès, Monsieur de Sotel, Monsieur de St Ouen. They spoke of themselves as the Noblesse, for in Jersey as in France, Nobility was considered to begin with the Ecuyer and not as in England with the Baron.' From N.V.L. Rybot, 'Social Life in Jersey in the early 17th century', Bull. Annuel de la Société Jersiaise, 1941 XIV (2), pp. 76 ff.

The same applied in Guernsey; Pierre de Beauvoir, for example, was known as 'Monsieur des Granges,' or simply, 'des Granges.' Elie Brevint, Minister of Sark, writing in his Notebook in the first quarter of the 17th century, remarks that 'In Guernsey they give the title of Maître to the Jurats, whoever they are, so they say for example Mre Brehaut, Mre Febvre. In Sark they say honneste homme M. and N. principally when writing.'

See: Actes des Etats de l'Ile de Guernesey, Vol. III. Actes des Etats de l'Ile de Jersey, 1524-1700; Société Jersiaise, 1897. Jean Dumaresq was very busy that year: see the Library's Copie d'une proposition faite aux états par Jean Dumaresq, Ésc. Connétable de la paroisse de S. Pierre: et logée au Greffe le 12 Août 1786, touchant le rétablissement des enquêtes dans l'isle de Jersey, en matières civiles, mixtes et criminelles.

In 1614, Thomas Le Marchant wished to be called upon to attend Chief Pleas under the title of gentilhomme, 'au rang des gentilhommes,' referring to the preceding case, and appearing to claim right to the title of Gentleman as Seigneur of the fief of Vaugrart.

Above is a 577 Year old Title Deed Transfer for the Fief Blondel in Guernésiais - Grant of the fief of Thomas Blondel in the parishes of St Peter of the Wood and Torteval, Guernsey, made by Janet Blondel to Thomas de la Court on 18 July 1440, attested by Jean Bonamy and Jacques Guille, jurats.  Copy purchased from the University of Leeds.
There are only 24 private Seigneurs of Fief doms in the old Viking Norman Islands of Guernsey and Sark :

Seigneurial Courtesy Forms of Address: Examples * Note that because French is still used in the courts and other formalities, these Norman version of the style is still used. 

John Doe, Seigneur of Fief Blondel et L'Eperons
Elizabeth Doe, Le Dame of Blondel
John, Seiur de Fief Blondel
John Doe, Seigneur of Blondel
Child:  Anna, Le Dame de Blondel
Rt Hon John Doe, Seigneur of Blondel
John Doe, Sgr. of Blondel
John Doe de Blondel
Pierre de Fief Blondel

MonSieur John Doe of Blondel

Lord (seigneur) was not necessarily a title.  The owner of a lordship, even a commoner, was its lord.  The term "lord"  meant "the possessor of a certain kind of property" in the feudal system, a mixture of actual real estate and rights over people (rents and fees could be collected from them, certain obligations could be imposed on them, etc).  Someone who was only a seigneur was not titled.  All FRENCH lordships disappeared when feudalism was abolished in 1789, but the Norman Crown Dependencies  of Guernsey, Jersey, and Sark still maintain their Feudal historical culture, customs and styles even today under the Queen and Crown.

Viking Styles, Honors and Titles - In Denmark and Norway , the title of  Friherre  was of equal rank to that of Baron,   which has gradually replaced it. It was instituted on 25 May 1671 with Christian V 's  Friherre  privileges. Today only a few Danish noble families use the title of  Friherre  and most of those are based in Sweden, where that version of the title is still more commonly used; a Danish  Friherre  generally is addressed as "Baron".  ^[10]  The wife of a Danish or Norwegian  Friherre  is titled  Friherreinde  , and the daughters are formally addressed as  Baronesse  .  ^[8]

Freiherr (  German:  [ˈfʁaɪˌhɛɐ̯]  ; male, abbreviated as  Frhr.  ),  Freifrau  (  [ˈfʁaɪˌfʁaʊ]  ; his wife, abbreviated as  Frfr.  , literally "free lord" or "free lady")  ^[1]  and  Freiin  (  [ˈfʁaɪ.ɪn]  ;

In France, during the  Ancien Régime  , French baronies were very much like Scottish ones. Feudal landholders were entitled to style themselves  baron  if they were nobles; a  roturier  (commoner ) could only be a S  eigneur de la baronnie  (lord of the barony). These baronies could be sold freely until 1789 when feudal law was abolished. The title of baron was assumed as a  titre de courtoisie  by many nobles, whether members of the Nobles of the Robe or cadets of Nobles of the Sword who held no title in their own right.    In 1815, King Louis XVIII created a new peerage system based on the British model. Baron-peer was the lowest title, but the heirs to pre-1789 barons could remain barons, as could the elder sons of viscount -peers and younger sons of count -peers. This peerage system was abolished in 1848.

Seigneur  (English:  Lord  , German:  Herr  ), was the name formerly given in France to someone who had been granted a fief by the crown, with all its associated rights over person and property. This form of lordship was called  seigneurie  , the rights that the  seigneur  was entitled to were called  seigneuriage  , and the  seigneur  himself was the  seigneur justicier  , because he exercised greater or lesser jurisdiction over his fief. Since the repeal of the feudal system on 4 August 1789 in the wake of the French Revolution , this office has no longer existed and the title has only been used for sovereign princes by their families.

In pre-republican Germany all the knightly families of the Holy Roman Empire (sometimes distinguished by the prefix von or zu) eventually were recognised as of baronial rank, although Ritter is the literal translation for "knight", and persons who held that title enjoyed a distinct, but lower, rank in Germany's nobility than barons (Freiherren). The wife of a Freiherr (Baron) is called a Freifrau or sometimes Baronin, his daughter Freiin or sometimes Baroness.

Families which had always held this status were called Uradel ('primordial/ancient/original nobility'), and were heraldically entitled to a three pointed coronet. Families which had been ennobled at a definite point in time (Briefadel or "nobility by patent") had seven points on their coronet. These families held their fief in vassalage from a suzerain.

What is a Free Lord ? The holder of an allodial (i.e., suzerain-free grant direct from crown to holder) barony was thus called a Free Lord, or Freiherr. Subsequently, sovereigns in Germany conferred the title of Freiherr as a rank in the nobility, without implication of allodial or feudal status.

Seigneur (English: Seigneur; Lord) was the name formerly given in France before the Revolution, and in New France and Canada until 1854, to the individual or the collective entity which owned a seigneurie — a form of land tenure — as a fief, with its associated rights over person and property. A seigneur could be an individual, — male or female (seigneuresse), noble or non noble (roturier) — or a collective entity such a religious community, a monastery, a seminary, a college, a parish.

This form of lordship was calledseigneurie, the rights that theseigneurwas entitled to were calledseigneuriage, and theseigneurhimself was theseigneur justicier, because he exercised greater or lesserjurisdictionover his fief. Since the repeal of thefeudal systemon 4 August 1789 in the wake of theFrench Revolution, this office has no longer existed and the title has only been used forsovereignprinces by their families.

In common speech, the term  grandseigneur has survived. Today this usually means an elegant, urbane gentleman. Some even use it in a stricter sense to refer to a man whose manners and way of life reflect his noble ancestry and great wealth. In addition, Le Grand Seigneur had long been the name given by the French to the Ottoman sultan. Notre Seigneur Jésus-Christ is the French equivalent of the English Our Lord Jesus Christ.

The word seignorage is also derived from seigneur.

The word shares the same provenance as the Italian Signore, Portuguese Senhor and Spanish Señor, which in addition to meaning "Mister" were used to signify a feudal lord.

Use in Crown dependencies

The title is still used in the Bailiwick of Guernsey.In particular, it refers to the  Seigneurs of Guernsey and the Seigneur of Sark

The traditional native language of Guernsey is Guernesiais (pronounced ‘JEHR-nehz-y-yay’), also known as Guernsey French or 'patois'.  However,  in the 11th Century Old Norse was the most widely spoken language in Europe.  The region was huge and consisted of all the Nordic countries, settlements in Scotland, Ireland, England Wales, Isle of Man, Normandy, Vinland (America) and Volga (Russia) and some places in-between.  As a note,  William the Conqueror understood the Norse language, and the names Jersey , Guernsey , and Alderney are as truly Norse names as Orkney and Shetland. Norse was actually spoken in parts of the Contentin in North Western France in places like Bayeaux. Norse was spoken and or affected many words and traditions in feudal guernsey.

Nobility of the Norse
https://en.wikipedia.org/wiki/Aristocracy_of_Norway

Modern aristocratic titles

In the last 300 years, the titles of baron and count,  title of marquis in 1709, the following system is the current in Norway or the Norse Nation.

The class of barons and the class of counts were even internally divided. A count would be a titular count (greve), a feudal count (lensgreve) or a national count (riksgreve). Likewise a baron would be a titular baron (friherre), a feudal baron (lensfriherre) or a national baron (riksfriherre). For example, a lensgreve uses the title greve only.