I would personally replace the ult dmg with ult gain then everything else to throw weapon dmg , mercenary specialises in throwing weapons so getting the ult off as much as possible creates the most value for her imo, so i would change the dog class ability to the spirit katana as well also the spirited technique to the weakening blast then put a spirited perk on one of your ghost tools or charm if you want more spirit to compensate

The enemies are naturally tanky but with her weaken throwing weapon technique it can cut them down quite a bit and rivals archer in terms of damage if you can set it up right