Are the Stormfall upgrades character bound or account bound? Meaning, do I share the upgrades between characters or do I have to upgrade for every character individually?

And before a lot of comments come about this: Yes I know you can respecc into any character and the need to have multiple isn't really there, but I am playing with 2 friends and we have a second char we only play together, so that's why I am asking.

Anyone know?