You can only have up to 4. If you use the skill again, whether you have WBs in your gun or not, you will only get up to the max your skill allows. Lv1 WB will always give you only one WB maximum. Using lv10 WB when you're carrying 4 already will just mean you still have 4 and wasted your skill.
You can apply all your WB to separate targets to have them all take 3x damage, but they'll all disappear in 15s so it's hard to take full advantage of. Might as well do that if you're going to switch weapons, though, since you lose all WBs in reserve.
Connect With Us