able to use the zweihänder with a strong buff but i'd say man serpent sword would be even better. i'm a bit astonishied how high i managed to get the hp and poise given that he has 40str and 30fth (with 10.8p weight for equipment and a fast roll)
less hp and defense but stronger spells and a max. scaling divine zweihänder
i'd recommend v1 as it offers more weapon variety but depending how much you want that zweihänder to shine v2 could be more to your liking.