The Shield is wonderful...
The Ram is deadly.
Isn't that how it always works?
But that aside, I have only spotted this thing twice. First time, as a black mage around level 15-16 farming sheep, I ran to the Dem and stayed my but away from it, watched three players die while two stayed on birds and stayed in my line of sight. One person managed to zone it.
Second time? Red Mage level 39 farming sheep for fun while I waited on someone, saw his name fly past my eyes on the Log and started looking for it. 75 RDM/NIN was killing it, half dead so I started curing him. That being said, a 75 RDM/NIN in good gear(he was in RDM AF- had been farming SB's 'little sister' Stray Mary so he probably wasn't prepared for it, don't know) should have no issue with it. I only caught half the fight and was too busy watching his HP bar to bother watching the log to see what it did... didn't think to check afterwards either...
Eh, this is my 2-cents worth. Hope to get some help and get the shield myself, will be very nice when I level up... (44 RDM currently).