It's a little more complex than that. It's not as if I can summon him all the time, you know? How do I explain it...

So, basically, when I originally summoned Archer in my world, it was utilizing the grail's power, but he was also connected to my mana.

I can't exactly 'summon' him the way you'd summon most familiars, due to his origin. Summoning a Heroic Spirit is too powerful, you see. But I suppose since I have no access to the Grail, my Command Spells are just moot, since those are directly connected.

I guess that'd be a different story if Archer was in this world, though. Maybe.