User blog comment:Adonis32/Brave Burst Info/@comment-25137187-20150516215229

Levels increase the amount of what ever you're doing.

I know I explained it horribly, so let me give an example;

A level 10 offensive BB (Brave Burst) does more damage than a level 3 offensive BB.

A level 10 healing BB heals more at level 10 than at level 3.

A stat increasing BB increases the stats even more at level 10 than 3.

"Do they all restart their damage values with the addition of new skills?" <-- Not quite sure what you're asking there. If you're talking about unlocking Super Brave Burst (SBB) or Ultimate Brave Burst (UBB), then no.