"Veteran" of the Mandalorian wars could mean that he served aboard a ship. my guess:
You were a Padawan on Dantooine just before the Mandalorian wars began. Lured by Revan's charisma and a youthful urge to fight for truth, justice, etc. etc., you left your training mid-step to go with him to battle.
You fight, you win. But something about the war disillusions you, or maybe scares you, and you become unsure whether you're really Jedi material.
You take off, in "self" exile, to rethink things. Along the way you fall out of touch with your training. You can still use the Force, but the disciplines taught to you at the Academy quickly leave you as you're out of practice.
I don't think we're going to see Kyle Katarn 2 here. We're essentially going to begin with (in d20 terms) a Level 1 Force Adept (regardless of what beginning cllass you choose) who has to re-establish him/herself and their destiny.
It *can* work...I just hope Obsidian does it right...