I passed my level 36 by killing those. They conned orange & yellow to me. Arracht was orange/red. They drop the Ollipheist Eye all right, and the stats for the object are accurate. It's a caster jewel. Aside from that, they usually drop meat, claw, fangs and sometimes a hide. I Didn't get anything else.
They are somewhat easy to kill, as i was able to solo a lot of ojs with my blademaster and they resist slash damage. Thrust & Cold seems to be the most effective damage you can deal on them. Sometimes they throw 2 attacks in a row, pretty nasty...
Anyways, plenty of fun, but for drops... kinda not the spot.