Hmm, all good points. On the other hand, apart from his tuuri-dive, it's not like Onni has done much either, magically or not (the main thing that springs to mind is VASTLY overestimating his ability to fight the Kade). So maybe they can bond over their sudden shared uselessness.
I do think Lalli has been helpful in some practical ways, mostly by dragging Reynir our of harm's way. I said magically because I don't think Lalli give Onni the emotional support he needs, but I should have said something different, like practically. That said, it doesn't look like he's been scouting for the team or anything, which he should be doing, and which Sigrun or Mikkel should surely advise.
Oof, now I'm talking myself into disliking all the characters.