Where do you find the bound bow?
There's a copy of the spell tome in Fort Amol Prison, under a lantern inside a bucket. Court mages will have the tome for sale once you've leveled up Conjuration to 50, I think (my conjuration is in the low 40's on my mage character and I haven't seen it for sale yet).
That's one of the spells my mage is trying hard to get. She'll use it as her primary soul trap weapon.