As a 62 SK I can solo these things in my sleep. You'll be able to get singles by either using harmony or FD splitting and the monk could probably solo it from there if you have decent equipment.
has dropped off every army behemoth that we killed so its a common drop. The mob it drops off of, however, spawns very rarely in the eastern part of the zone (the easier part) and quite commonly in the western part of the zone on the ramps heading towards Neh'Ashir. 59 monk and 53 druid MIGHT be able to do it if they can handle 3 or 4 at once without crowd control. Add in a pally or cleric who can pacify or a chanter who can mez adds, and you stand a better chance.
Full group of low-mid 50s, and absolutely no problem.
Picked up one of these last night from An army behemoth (green to a level 60). I have been clearing out the ground floor of CoM off and on for, oh maybe 24 - 48 hours and this is the first I had seen this mob spawn. If it matters he spawned on the northern deck of the bridge in front of the castle.