3) There is a Spear you can find that deals additional damage to enemies with multiple eyes and has a chance to blind them. You may have found it by now if you dealt with the owlbear.
Legitimate point, although, I only tried using the spear on a spectator once or twice, and it truly didn't seem to have very much effect at all worth noting; blinding the spectator (when it worked) didn't really inhibit it much. It certainly didn't stop its eye rays. On a related point, I'm generally not a fan of "Here's this overtuned fight, but here is also a special magical maguffin that is only going to be useful in this fight that will make it better." It's a cheap, dull and utterly uninteresting story mechanic and even worse as a combat device.