I found this just today, I am no means a shining force veteran, but I'm enjoying the mod, it's a fresh take on nostalgia for me and it's very evident that this is an impressive and time consuming endeavour, wow!
Unfortunately capt. addington is a bit of a hurdle, even with magic elixers and two casters going at him I've probably pumped well over 300 damage into him and his health just keeps going back to full every round (bug or intended?) and his defense is too high for the physical characters at level 4/5 even with the best shop equipment they can have, so I'm a bit stuck.
Edit: I got it! He was tough though!