once you realize Shabon's uberness, you can further the chaos by pairing her with Sgt. Joe. it's a *very* large area unite that does 1.2x dmg to the target and .6x to the surrounding.
for unites, i find Accuracy does matter, as enemies can guard, taking half damage or sometimes 1 dmg (it matters for her Lion Rune setup as well, actually, but i've never seen an enemy take 1 dmg from the Lion Rune)
by the time Hugo can recruit Shabon, you will basically have some Gale (Hugo chap 1 and 2, Bunnies in North Amur Plains)and Fury Runes (Bronze Suns, Ancient Highway chap 3), and maybe even a Double-Strike Rune from Mt. Hei-Tou.
she won't have a lot of rune slots until later, though.
at full capacity, the Mounted unite will have so many multipliers you'll be dizzy. 5-6 swings from Shabon, 2 or 3 from Joe (3 is tough to reach without a Gale Rune).... Shabon can use Double-Strike, Fury, and Warrior/Gale. Joe can use 2 runes, choose from Fury, Double-Strike, and Gale. work with Joe's Damage skill (can he wear Flame Casque?, plus Gold Beaks to reach the next swing then Silver Beaks to fill the other Accessory slots) and Shabon's swings (speed equipment to try to get an extra strike or just increase dmg.. Wind Hat, Feather Earrings/Belt of Strengths, and Taikyoku Tunic for more speed or True Thndrblt Leather for increased accuracy).
with these two, you can pretty much take out the entire enemy party before they attack. if you add Jeane (maybe other Rune Sages as well) as support, you can also combine it with the Jongleur.
and finally, since this unite is so useful (greater than 1x dmg to a boss but still covering an area for random encounters / boss' sidekicks), to use it every round (vs a boss) give Joe a Balance Rune.