As I recall it was the bow of a legendary Elven hero- Taulmaril.
It was a major item, and Cattie-brie was competent with it from the moment she picked it up.
It seems to ignore armor/natural armor bonuses to AC, and slice right through most forms of cover less than a foot or two thick.
Then there's electricity, thundering, and radiant...
I though most enhancements carried over to have the bow cause the effects on the arrow. The quiver just restocks itself.
I am fairly certain it would qualify as a Lesser Artifact, based on the other lesser artifacts that were once the top magical items in 2nd - Hammer of Thunderbolts, Staff of the Magi, etc.