[ Servant using other Servant as battery just sounds like a lot of trouble. Even if the shinki nature seems to tamper with the "Servant'y" nature somehow. Lancer either doesn't have his weapons or haven't realized yet he can get them. Berserker... he saw her only once so it's impossible to determine if she has her- either way, it seems neither of them possesses the access to their Noble Phantasm, and if they energy replenishes normally...

That might mean they might not be Servants at all, just souls of dead, famous people- but if that's so, the class-confusion shouldn't be even part of it-- argh, Heavens, why you make no sense ]

I know you're offering because you're going to enjoy this. [ Duh, you twisted, sly fox ] Ah, with my luck, of course, I had to get stuck with unmanageable shinki. So I can only make sure I'm equally handful of a god.

[ So there is equivalent exchange of giving each other trouble ]