They are soooooo easy! <img src="/ubbthreads/images/graemlins/biggrin.gif" alt="" />
Just boost your "sharpen" weapon skill, and use it to increase your sword damage dramatically. My characters are level 19 and kill those monsters in a few hits only.
Note: be sure to have enough agility though, or you will not be able to use
your favorite sword for a while.
Another solution is to use appropriate arrows from far away (don't remember if it was air or water. Check in the trophee screen to see their weakpoints).