Go to Brindle Home, north of Skingrad. You will find a man named Torbal The Sufficient. Kill him and loot his corpse. You will get a lot of enchanted arrows and the Bow of Blizzards. This is an enchanted bow that does 20 points of ice damage. If you equip this bow and the Arrow of the North Winds, which does 60 points of damage on its own, you will have a very strong bow.