Validate number of skills does not exceed a total of 3. Since the slots for set bonus skills can be used to add more than 3 regular skills, and having more than 3 regular skills per piece crashes the game, this should be validated.
Validate number of set bonus skills. Since the slots for regular skills can be used to add more than 2 set bonus skills, and having more than 5 set bonus skills in total crashes the game, a warning should be shown.
See issue #3.