Now for starters...
I've found the best way to level up in chronicles of sword.
Get through all the way up to chronicle 20 as you normally would.
(create a second c.o.t.s. save so you don't ruin the original)
Then at chronicle 20, create a character of the class you want to level up.
They will start at level 1.
However, because the opponents in chronicle 20 are all at level 50 or higher, it doesn't take long to level up.
So how do you do it since the levels are so lob-sided?
Well, use your entire group on the map against 1 enemy at a time.
Right before the opponent is killed by your group, select the character you wish to level up and select battle.
This will make it so you only need to land a few hits or maybe one throw to defeat the enemy.
Using this tactic I unlocked all "soul of..."
Also, get this...
Using this strategy I was able to level up from level 1 sage to level 30 sage in only 8 battles (all wins).
Now for just a few more things...
I beat night terror finally.
Also, I found that you can pretty much use any path and as long as you never lose and always select to face opponents that are mysterious or watching you...
back later... till then,
-Kent