All weapons either have fighter bonuses or mage bonuses. The unusually large stat bonuses on weapons will not overpower the party too much until endgame because I subtracted their bonuses from each character's base stats. Characters will start the game with their base stats, and while they won't get temporary +whole numbers from gear, their stats will grow more uniformly and somewhat faster. In this way, you can't tell the character from the character+weapon, so I effectively only changed the stat growth rate. Note: for complicated enough reasons, I recommend not allowing temporary members Blank and Marcus to level, or else following the steps at bottom to set Amarant and Eiko (respectively) right later; elsewise, it'll throw your stats off.
This approach also keeps the characters' relative stat strengths in tact. The only differences bigger than +/-2 compared to mixed-gear-bonus ordered totals are the following. Firstly, Vivi, Freya, Quina and Amarant didn't have stat weapons, but since they now grow uniformly based on their personal base stats, their key stats are much higher. Again, they fall into the same ranking they did naturally, independent of whatever gear is available to them Secondly, I didn't mimic the +Mag Steiner and Freya had, so their Mag is more comparable to Zidane's and Amarant's than to Quina's now. This all balances the characters' personalized natural stats with the maxes that the game already made possible.
To answer the difficulties with Spirit, the most desirable and main max-able stat, I gave everyone the same Spirit growth. I settled on the bonus value that gets almost everybody to 50 by lv99. They don't have too high Spr for most of the game because, again, I subtracted the weapon's bonus from their base stats. Characters who boast naturally higher Spirit get to max earlier; the less spirited don't have that advantage, but get there by lv97 at latest (Amarant). Only Quina doesn't get to 50, but the growth that would be needed for that would make others max Spr unreasonably early (like lv64). Singling Quina out for a bigger bonus would negate others' having higher Spr in their particular strengths and weaknesses.
Quina gets to 46, and whoever prefers round numbers to characterization just needs to level up some with some of the Hawaiian set. I am putting +4 Spr on each of the four Hawaiian items. The exact number of additional SprBonus Quina needs to get to 50 is 114, so all four pieces for 8 levels (114/(4+4+4+4)=7.125 levels needed) is the shortest route. Even going through the whole game not caring about stats or levels, it shouldn't be hard to get the Hawaiian gear and remember to put it on at least before passing Quina's lv91. In case you need other gear on to level Quina for some reason, other combinations of +4 accumulating over levels and summing at least 114 will also work. Using the otherwise useless Hawaiian gear is a good way to enable all 50s for Spr without worrying folks about their gear (the point of this mod) or tampering with the characters' natural strengths, weaknesses, and growth.
On another note, I chose Magic-ordered Quina because taking the approach described above to its numbers fits in 100% perfectly with the party's natural Str and Mag rankings.