This simple script allows you to set level, skill and switch conditions to traits for actors, classes and enemies. Not flashy or sophisticated but it does the job.
Use notetags in the desired database tab with the following syntax:
<trait_condition: x, y, z>
x = the trait number in the field (note that it starts at 0, not 1)
y = three possible strings: level (for actors), skill (actors and classes) and switch
z = either the level threshold or the switch/skill ID
Note for version 1.05: switch condition is available on equipment as well.