FYI: You keep static buffs from different stance upgrades.

[ThoricSatsuma37]

Not sure how widespread this knowledge is, but you can currently get 100 HP, +10% Max HP, +10% stat bonus, and +10% Energy Regen from each weapon stance. These persist regardless of which weapon you're actually using.

I wish the final perks did the same. I'd love to have ghostly archers, phasing, periodic invulnerability, shroud, bloodlust, and berserker's fury all together, plus a free helm enchantment slot...