Good fort fighter in short? From the most important to the least important:
- don't play adventurer class
- get the best fort gun possible for your level, avoid 1-x guns (most wanted is prec. winchester or gold gun, doesn't matter, but get one of those two)
- get 130-150 leadership (equipment included)
- almost everything else put in STR (AP) and HP (SP)
- get the best equipment (if soldier then items with HP bonus, if not soldier pick items that provide most points in relevant ff skills)
- get experienced with movement in fort fights
- be nice to generals and always try to squeeze out captain rank
Crafted items are useless unless you're usually in top 10 at the end of the fight and want steellined box. In that case pick bayonette if you're after #1 spot on total damage or +3 DEF for dodging stat.
The only crafted item that would be generally useful in fort fights doesn't exist. Yet. Such item would boost your luck.