Passive Boosts class locked? (FEBuilder)

Any way to make Passive Boosts class locked in FEBuilder?

That was a uh…minor detail I forgot when I was attempting to implement the Knight Ward from FE9.

Any clues?

Passive boosts were not made with this functionality in mind, sorry.

A way you could do it is make the effect a skill.

If unit is [Armor type], give stat boosts.