We'll be getting the +30% defensive growth scroll at the start of the next map, so Marita might want to wait until then, though she doesn't have to by any means.

Anyway, bringing all the unbenched mounted characters leaves us with... negative four slots. We don't have space to bring all of them, particularly since Chapter 10 has us with guys like Bryton and Hicks not on the bench yet, so actually go back through the list and pick some like a reasonable person.
If you want my recommendation for mounted units, I'd bring Fergus and Carion, naturally, Nanna for the heals... Uh, Fin, I guess, if you want to go all-mounted... There's space for Olwen, but you could use that spot for one of the mages and have access to extra staves that way, too.

There's nothing particularly worth stealing.

Of the people on your list (That is, mounteds) who are in the zone where promotions might be thought about...

Fin promotes to a Duke Knight, like his buddy Glade there. This offers him +2 Str, +1 Mag, +3 Skl, +2 Spd, +2 Def, +1 Con, +1 Mov, +1 Lance Rank, the last of which doesn't mean anything to Fin. Not great, but Fin's starting to lag; he'll need these to keep up. For Fin, this is probably the point in the game where you decide whether you're with him all the way, or whether he's about served his purpose. It's a hard thing to face, but that's life.

Fergus promotes to a Forrest Knight, a class he shares with exactly one other unit.
In terms of stats, +2 Str, +1 Mag, +3 Skl, +3 Spd, +2, +1 Con, +1 Bld, +1 Sword Rank, the sword rank being irrelevant to Fergus.
Forrest Knights (Uh, you sure you've got that right, Serenes?) suffer the lowest dismounting penalties in the game -- just the movement penalty (and with his boosted move, you wouldn't even notice it on Fergus. He moves as fast as a regular foot soldier off his horse) and a -1 penalty to defense. That's pretty handy, since the endgame is a series of entirely indoor maps. The stat gains are slightly better than Fin's (by 1 point), but on a unit whose doing all-around better to start with, and has better weapon options as the game goes on as well, and into a slightly better class, too: by the time he gets to level 20, those bonuses may well catapult Fergus into striking range of maxing a few nice stats, without ever having to do much in the name of all-scroll arena-grinding. And that just puts a smile on my face.

Carion promotes into a Paladin (Male). Well, it's not that male and female paladins are different. It's that someone coming to Paladin from Cavalier gets a different promotion than someone coming to it from Troubadour, like Nanna. Anyway, stat gains are +2 Str, +1 Mag, +3 Skl, +2 Spd, +2 Def, +1 Con, +1 Mov, +1 Sword Rank. Someone knows his place in the world is to tank, and Tank. He. Shall. That strikes me as being the best thing about this promotion compared to some of the other ones, though Carion sure could use more sword rank. Like Fergus, he stands a good chance of having a good many things capped, though he's had a lot more help getting there.

Robert Because you asked about mounteds, although I'd not recommend him here, since it'd be hard to cover for not one but two archers, Robert promotes to a Bow Knight, with +2 Str, +1 Mag, +3 Skl, +2 Spd, +2 Def, +1 Con, +1 Mov, +1 Bow Rank bringing him to A Rank Bows, and who knows what else. His spread is basically just like Carion, although, really, while he gets proportionally more from the defensive boost, he's also less inclined to use it, except maybe for wall-sniping battles (very possible).



Since she's coming, here's Karin's...

Karin promotes into a Pegasus Knight, for gains of +2 Str, +2 Mag, +2 Skl, +2 Spd, +1 Def, +1 Bld, +1 Mov, +1 Lance Rank. Simple and well-rounded, though she hardly needs the speed. Still, the rest of it won't be missed at all, even if it is rather dull. Pegasus knights are, on the whole, less impressive than dragon knights stat-wise, but also take less of a giant penalty come dismount time.

Also, since you were interested in spare healers, I will mention Safy's as well, though I think this is more for future reference: she's squishy enough that I don't want her in more ballista-filled maps, please thanks.

Safy promotes to a High Priest, with stat gains of +3 Mag, +1 Skl, +1 Spd, +1 Def, +1 Mov, +1 Staff Rank, +1 Light Magic Rank. To be honest...Safy, our Safy, would not get a lot. She's a single point away from maxing speed. We don't own any light magic yet. She's an A-rank staff user. She's maxed magic and skill. Basically, she would max speed, get a point in defense and move, and would get the ability to try and keep raising her Luck, Move, and Defense (the latter of which are pretty unlikely).... And get to hurt people, althought hopefully only people who'd never try to hurt her with anything but magic. When we get tomes, anyway. It strikes me that, as miserable as it feels to run someone who gets no EXP from taking actions, when we need a staff rank and/or a heck of a lot of magic on a healer, we can just use Safy perfectly as she is and not notice the difference until we get more Knight's Proofs, and use other staff-users, maybe train up our Elite Manual holder and Tina or the like when we want people besides Nanna in the meanwhile. I leave it to y'all's discretion.