Who else is lucky and unlucky at the same time?

5* Jakob? That must be a lot older than just 2 months then. You can do something with all of them even with a bad IV, but it depends on whether you actually like those characters. If you don't like them, then just fodder all of them once you find someone who can use one of their skills.

At first glance i thought it was HJakob, ugh. But still even with bad IV you could make it work with 5*. Or else wait for merge or fodder them.

I'll just offer some ideas on the heroes I know about

Eirika: probably fine with her base kit, actually. Her spd isn't marred. If you feel that she doesn't hit hard enough, give her a blade tome and support her with hone cavalry. She will definitely destroy everything. If you don't want to invest to give her a blade tome, I suppose you could fodder the swift sparrow.

Kana F: what you end up with now is a very flat statline. If you take lightning breath+spd and warding breath, for example, you can do the conventional aether+QR thing and tear up PvE, and she has significantly better def than Fae for having around the same spd. If you don't like the statline you have on her you could consider foddering goad dragons.

Saber: I don't remember him being actually that fast; he can build just to take infinite melee hits with double close def and keeping his shield pulse. He probably won't kill anyone that way, but he can protect the teammates who do all the killing.

Mia: with QR and something like darting stance or spd/def bond, she can block doubles from Ayra and Karla and actually one-round them. Alternatively, there are units who could use her flashing blade (ex: the AoE quasi-OHKO build I made for Karla; smoke dagger + miracle debuffer).

Lute: I decided to look at her character page. The IV is actually fine, if you ask me. I would prefer a boon other than def, but really, it's not bad. Her trademark is ploying, and she hasn't lost any ability on this front. Here's one build that works on your IV:
Weirding Tome
Moonbow
Fury
Desperation
Res ploy
Atk or def ploy (to support the team)

50 atk (55 if you count the res ploy) and 38 spd (43 if you count the ploy); she ploys on 37 res, and if she gets hit by a DC blue, she can survive up to 55 atk from them. Unlike blade tomes, she doesn't suffer cooldown penalty, so 50-55 atk can be quite convincing.

Legault: maybe good for sweep debuffing, but I'd probably fodder the atk tactic. His atk is very low to begin with, which doesn't matter if debuffing is all you care about.

Elise: not a nice IV, but doesn't matter that much if you're using pain+ double savage blow and healing the rest of the time. It is worth noting that she will now probably survive one hit to her def. She has also kept all of her ploying potential.

Jakob: might be reasonable for some kind of close counter QR build, but I would probably merge into a different IV because he's 3*/4* available. However, if you want to use this IV it might be doable.

Cloud maiougi+res
Sol
Close counter
Renewal
Spd smoke
QR

Ideally he doesn't want to use close counter with this weapon because he'll want extra atk, but here's how this build tries to get around it:
1. He doesn't need extra spd when getting initiated on unless he would get doubled, but dragons are probably slow enough. If there's an issue, get some ally support or a buff.
2. Once he's been hit, spd smoke hits the rest of the opponents, so if he wants to initiate on another dragon, he might have a natural double.
3. Effective damage means he's hitting for around 57 minus their def, which in some cases might score a KO.
4. If two hits won't do the trick, it's ok because the dragon is initiating, which means he probably won't get hit twice due to the dragon's QR. He can initiate on some fresh dragon and heal using sol while his teammate finishes off the dragon that attacked him.