[Snake]

That's honestly a good thing to tackle. 'Training' should yield more if the people fighting are close to the 'average level' of the combat. Add all levels together, divide by the number of people. Then subtract from the party members' levels, to determine the EXP%.

Or make the EXP be rewarded -during- combat, when you accomplish certain feats such as Backstabber, or Soaring, rather than making those just some small bonus.