Beelzebub raised his eyes for a moment, both to let a flash of amusement cross his face at the Sin's comment, though he does not respond, and to catch his Master's smirk. They really are lovely blades, one of a kind and a recent... acquisition... he'll admit to being terribly fond of.
He fades a little then, standing back to casually watch the proceedings once more, a subtle attitude of uncaring layered with the the stance. His whole attention though, if focused on what is going on, the interaction between Lucifer and Greed.