Got it and managed to get Endurance Master on 2nd try. Though what I did was this:
1. Equip "Who Knows"
2. Save.
3. Get into fight and see if got extra turn.
4. If no, reload, unequip and re-equip "Who Knows" till you get extra turn.
It works for those looking to keep a low Defeat or Escapes count.
Now, just got to figure out which others were activated.
Tip to get desired skills:
Well, don't buy too many skills till you get Who Knows. Works better with characters you haven't used so far, if you choose to use them later. I plan to use it to get desired skills on Trisha, Gorodo and Zolerus in post-game. Only skill they all got is Poison Resistance.