Rhor's 4th Skill slot

Rhor's 4th skill slot is empty when he reaches level 40. At level 40 he has the following skills, Lightning Strike, Lightning, and Ultrasonic. This is the only monster I know of that has an empty slot at 40. Shouldn't he keep whack, and Lightning strike go in the 4th slot?

Griff is also a 3 slot mob

Griff is also a 3 slot mob

See, to me thats crazy! Why out of all the monsters in game are those the 2 that get a 3 slot deal?

Well its not really a bug. Because its working as intended.
Just bad mob/skill/evolution design.