How many characters to focus leveling on?

[Farel]

I'm on my second playthrough. I'm manage to beat the basic versions of the Scarlet Fiends, and the prospect of fighting their true versions horrifies me. I would dedicate my next playthroughs to get as many skills as possible to expand on my selection of roles.
I have a question regarding "my crew" that I planned to have:

These have tons of skills, and will only get better with future playthroughs:
- Leonard (Greatsword, might get Clubs next time)
- Mondo (Spears, might get Bow and Longsword in the future)
- Ogniana (Axes)
- Angle (Daggers)
- Urpina (Longswords)
- Elysed, Arthur & Mirane (Mages basically)

They're a bit behind, but I might work on them:
- Tsubaki (Daggers)
- Griffin (... Bows?)
- Lewis (Martial Arts)

I only barely touched these (Elisabeth not at all)
- Kumi (Greatswords)
- Kahn (Spears)
- Elisabeth (Clubs?)

I just had to think about it all and how much of an overkill this is... 14 characters... How much it'd take to make everyone know the same techs, plus all techs ... It seems like much work for ultimate bosses, where I'd be lucky to use a third of them...

Is there any advise for making priorities here? Only having 5 people would be not enough, I'd need specialties... Which "archetypes" or weapons work in a way where it'd be advantageous to have more than 1 person which is good at them, and which are fine to be kept at just 1, or outright have the character have said weapon be something used on the side, next to their true specialty?

Also, are some of the picks that I make for the characters and their "thing" debatable and I should reconsider them?