Welcome to the Nasuverse, where looking up famous legends is now spoilers! well at least it's easier then Assassin's Creed where pretty much History itself is a giant spoiler.
Skribulous said: Yes, because no one pays attention at the end credits starting EPISODE 2. Nice try, though.
Uhmmm, the end credits don't explain who Berserker is. We just see his back and know he's some long-haired knight.
Granted, anyone with some deductive reasoning could figure out he knew Arturia, but that doesn't mean they would deduce he is Lancelot. You'd have to bother researching Arthurian legend and seeing who fits Berserker's abilities of using anything as his weapon and disguising his true identity to have a chance of guessing it.
So, yeah, Doc Visigoth, Wakamoto, and Skribulous, it is a spoiler. Ryvian raises an excellent point. Not everybody watching the show and checking out fanart here hangs out at the Type Moon Wiki or has read the original novel.