User blog comment:VedranTheII/Pretentious Diaries 2: What tricks would you teach your Aura?/@comment-26512661-20150718155058/@comment-25555436-20150718223453

But SAO has the excuse of being inside a videogame. It's justified. In Real Life it would shatter, but Videogames are not Real Life, especially high-fantasy ones.

Shit series, yes, but not for that. If the programmer or devs made a weapon of "obsidian" that didn't break in a game, it won't break, realism or not.

Also, just found the method used by the Aztecs for their weapons. The blade and hilt of their swords were made of wood, while the edges were the only obsidian segments. Strong enough to decapitate people a la Game of Thrones, and doesn't shatter so quickly.