He is (though his lack of expression does not signal it) happy to take the crossbow, and listens to Sonja's instructions, giving her a quick nod before she dives in.

It's not easy to tell what's going on in the water, and he does end up having to fend off another eel anyway, so when he looks again... uh. Well, he has the knife in one hand and the crossbow in the other, and he'll make a valiant attempt to keep his eye on the waters for when either or both of them resurface.