This comes from a discussion on the Lehnsherr name for Magneto, from Tilman 
Stieve (menshevik@aol.com):

Re. the Lehnsherr name, if I may quote myself from a message I sent to Rivka
some time ago:

"Lehnsherr cannot be Magneto's real family name. It sounds bogus; the word
(German for "feudal lord") is a scholarly term used by lawyers and historians
that probably did not enter general usage until after the feudal system was
abolished. To clarify: A Lehnsherr (feudal lord) was someone who "leant" a
fief (Lehen - the word is related to "leihen", to lend) to another person who
swore an oath of fealty (Lehnseid) and thereby became the lord's vassal
(Lehnsmann). In some rather rare cases, the fief would merely be a farm and
the vassal might then be a peasant (hence family names like Lehmann and
Lehner), but in most cases the fief would at least consist of several farms
(and the landlord's prerogatives over the peasants living there) and could be
as big as a county, a dukedom, in some rare cases an entire kingdom. Most
vassals would at least be knights and could in fact be anything up to the
rank of a monarch (in the top ranks a liege might have vassals who had
vassals who had vassals and so on), although of course a duke might be king's
vassal in name only. The term "Lehnsherr" was applicable to everything from
rich and powerful knights to the the peaks of medieval and early modern
society - emperors, popes, kings etc.

While the feudal system existed (i.e. before the late 18th century), no
non-Christian was allowed to become a Lehnsherr. (And it was by no means easy
even for rich Christian commoners to become a lord). Since antiquity, Jews
were discriminated against in Christian countries and during the feudal age
they lived outside the estates in which "respectable" society from monarchs
to peasants was organized. To become a vassal or a (full) citizen of an
autonomous town you had to be Christian. At least from the Crusades until the
Age of Enlightenment, Jews were barred from most professions (including
farming). Broadly speaking, they were not allowed to own land until the
French Revolution. Even for their town houses rich Jews frequently had to
employ gentile "dummy owners".

But many European Jews did not have family names until the state authorities
forced them to in the 18th and 19th century. There are Jewish families called
Lehmann. So could an ancestor of Magneto have adopted the name "Lehnsherr"
then? 

Sorry, Lehnsherr is an unlikely family for anyone (I certainly did not find
it in the two pocket dictionaries of family names at hand). Anyone who was a
feudal lord would, as a nobleman, already have a family name. The only other
way such a name could have arisen would have been after a person's master.
But family names refer to what set the original owner apart, so comparable
names would arise because a peasant had a different lord from the rest of his
village. And people obviously would have gone for the concrete (hence the
origin of the names of many families called Kaiser, Koenig, Bischof, Herzog,
("emperor", "king", "bishop", "duke") etc.), not the unfamiliar and abstract
term "Lehnsherr"."

As I mentioned above, I was unbable to find an example of "Lehnsherr" as a
family name in real life, although the possibility could not be dismissed
totally (after all, scholarly names were all the rage during the Renaissance,
and it really is amazing what names do exist in real life -- even some one
might think of as unprintable).

However, the analogy with British family names like "Laird" and "Lord" is
misleading, because "lord" is not a technical term as "feudal lord" or
"liege" would be. The normal German equivalent of "lord" is simply "Herr"
("The Lord (Almighty)" is "Der Herr", the sovereign is "der Landesherr" (the
lord of the land) and a few German states used to have a Herrenhaus (House of
Lords) until 1918). The German family names "Herr" (yes, there are people you
have to address as "Herr Herr") and "Herre" originated as names which were
stuck to peasants who were dependants of a minor nobleman (who might be known
as the Herr von (of) so-and-so) to set them apart from his compatriots who
might either be free or dependants of a cleric or a free city etc. (The
diminutive form "Herrlein" is however said to derive from the first name
"Hermann"). I guess the same applies to Britain, although I think that the
term "Herr" in German encompasses both "lords" and "esquires".

But I guess the real reason I do not like the name Erik Magnus Lehnsherr is
because it was invented by Fabian Nicieza and I found it impossible to
swallow that everyone who up until XMU #2 had called Magneto Magnus suddenly
called him Erik.

That's all for now.
All the best, and take care,
Tilman