There is a thread on this a little bit lower, but i thought this would be easier for you. The bow is called Stormfire.
StormFire this bow rocks. but you have to do something like 12 quests to get it, and they are all in stormhold. most of the MOBS will be grey to you which is actually pretty nice because you can breeze through quite a few of the quests in 15 min. span per quest. you will have to camp 4 or 5 named which can be tedious, but the bow is very much worth it, and your interection with the quest NPC is pretty funny.