Grim Weapon, Furor vs Arcana

In my Warden playthrough I got a Grim Bow a Grim Runic Sword and pretty early on a Ring of Arcana +0. The Imp gave me a Ring of Furor +2.

What do you think I should upgrade and wear? Arcana for a higher chance of Grim activation or Furor for a higher chance through more shots, especially since it's already +2.

I'd rather not wear them both because I like my Chains and Chalice too much.

Edit: I ended up with Furor +6 because I just like the fantasy of her firing off arrows like a machine gun. Should've enhanced it for speed, but that often means for the bow that it regularly does 0 damage in later levels. But I guess Grim would have offset that.