Like the Assault Bhoots, these skeleton types use an AOE Drain move, that which combined with 30+ melee beating on it gives it the ability to spam the move unnesessarily prolonging the fight. The good news is that it doesn't use it nearly as frequently as the Bhoots do, but it will do more damage to you than the Bhoots will, so I avoid fighting these in unnecessarily large groups.
Of course, I'm a thief with crappy piercing daggers, so I avoid fighting these, period.