Eddie has seen you crying about being deserted by your lover, so he has some more sympathy (and understanding that you're not necessarily a monster). Also he's down on the ground and you're up on the wall... okay, closer now, but still there's a physical distance. The physical distance makes it less freakout inducing.

"River's work," Eddie says, with pride for his friend. "I've been practicing with it for a while, and I feel ready to help out."

And that's 'help out without endangering everyone', since he has a feel for the weapon and experience in bashing things with it now.