There's one for summoner and red Mage, so here we go.
Personally, the big thing I'd like it UTILITY. I know they have this thing about keeping one "pure" melee DPS and one "pure" caster DPS, but it always causes issues (either people complain the classes do too much damage or they get kicked out of parties because they bring nothing to the table). I'd like something different than "just more dps" as the tools we have are already cover most aspects of that.
Looking at a game like FFT, Samurai could give various party buffs and enemy debuffs like Confuse, Doom, Regen, Haste, Protect and Shell.
Obviously, most of those wouldn't be good, but a skill that improves party haste might be decent as well as unique (though I'd worry about it messing with rotations). Or maybe something to increase DH rate to compliment DRG and BRDs crit buffs.
I'm actually curious to see how they're going to avoid bloat as I make use of every single Samurai ability I have now as it is.