It's somewhere between, really. He'd been holding a silver knife, after all -- Lancelot is aware what works against a fae. When he'd picked up the bin he'd hoped it might have at least a little iron in it, but it's pure dumb luck that it seems to. Luck he is very glad to have on his side right now.

The disgusting stuff splashes toward him and he catches it on the lid, makes a face as it starts to burn through the metal and the thing starts to scream. It makes his ears ring and he's disorientated by the sound a moment, recovers just in time to drop the lid before it burns through too close to the handle he's holding.

His ears still hurt, but the thing is running away and he's not about to let it go throw horrible acid at someone else if he can help it. He shifts to grip the actual bin itself and darts after the creature to take a swing at it. He is going to trap the horrible thing in this bin if it's the last thing he does.

After that, he's not sure what the plan is. He'll work on that bit if he gets that far.