Feels like an isolated demand for rigor: it's pretty standard to just take a bunch of medieval weapon names and haphazardly slap them on the different models in the game.

I don't know that that's that big a deal: you certainly don't go to a Diablo game for any sort of realism, and the names are based off real-life words that don't really have a match in most fantasy worlds.

"Claymore" is just derived from the Scottish for "great sword". Scotland isn't part of Sanctuary, so we've already lost the thread, the word is essentially meaningless in Diablo's setting.

And if we try to resolve this with something like "the word isn't actually 'claymore', it's some word in the language of Sanctuary humans that translates to 'claymore'", well, that also means it basically just translates to "great sword", and now we've got a great sword named "great sword", which seems to work fine.