If you want to get higher-tier schematics for the Advanced Bow, you will need to do some exploring, and the Legendary-tier version can be found on the Level 60 Oil Rig southwest of Feybreak Island.

You can find the schematic in two ways: Small chests on Level 60 Oil Rig Golden chests or Supply Drops on Feybreak Island If you want to have the best defense build, don't just rely on your armor.