[Morthoron]

I think it's less a matter of naming conventions fitting Elvish historical personages, and more a feature of the Hobbit squirearchy putting on airs. That, and Tolkien having a bit of fun.

Ever notice the further one goes up the fantastical family trees of wealthy Hobbit families, their names get more and more absurdly non-Hobbitish? Climbing up the geneological ladder one can't help finding a wealth of grandiose appendages tacked on to scions of high houses:

Scholarly references in Gerontius (perhaps from Cardinal Newman's "Dream of Gerontius"), Isengrim (Latin Ysengrimus, the wolf from the Old French fabliaux "Reynard the Fox"), Adelard (Adelard of Bath, a scholastic philosopher), Odovacar (a Gothic king) and Heribald (mentioned in Bede's "Historiam Ecclesiasticam Gentis Anglorum"); Latinate forms Belladonna, Hugo and Gundolpho; from Spain, Esmerelda, Ferdinand and Sancho; the Welsh Meriadoc, Gorbadoc and Gormodoc; a smattering of Germanic in Filibert and Gerda; and lastly, Frankish or Norman Odo, Otho, Otto, Fredegar, Paladin, Peregrine and also Pippin (from the Frankish Pepin, first king of the Franks and son of Charles Martel).

And then there's poor Samwise, holding up the ladder like all stolid Old English peasants.