Naraka
If Lex had known he'd be put on the spot like this he would have never made the sword to begin with! Or maybe, he would have just spent some time thinking of a name. Should he use a pun involving his name? The Lexicon?
No, that was dumb. Should he fuse his and Orin's name to pay tribute to the sword maker? Lorin? Orix? Hmm, still pretty meh.
Butter knife 2.0? It was tempting, but the sword deserved a serious name that sounded cool and intimidating at the same time.
Time seemed to slow down as thousands of names went through Lex's mind, but the more he thought about it, the worse his ideas became. Although, admittedly, that was because Lex kept thinking of different renditions of the Lexicon.