I'm not lying, if I was going to lie I'd come up with something more believable.

Try to use your shield. Go ahead, I'll wait.

[And yes, that's the final bit of proof he needs, and it's an odd feeling. On one hand, it's Greed and he can't stand Greed. On the other...he's familiar. Envy knows exactly where they stand and there aren't going to be any bizarre surprises. It's a relief.]