Oh wow, I really love the flavor that went into the skill builds here. Such a great translation of the characters' skillsets from their home games! FEH has such a great combat system for this kind of thing. It's not surprising this thread is already 28 pages long.
Re: Colette - Angel Feathers and Holy Song are pretty perfect translations of Colette's general Healer/Buffer/Holynuke build. And Colette's Chakram as FEH-style Daggers is pretty cool, though I'm not sure a debuffing effect is the way to go here. She doesn't have any real debuffing focus in her Symphonia skillset. That's definitely more of an artifact of FEH Daggers. Perhaps some sort of Brave weapon effect to reflect her multihit combo strings? Would need to add a suitable drawback to avoid another Reinhardt unbalance, though.
Re: Mikleo - Seraphic Artes is a cool idea, though you may want to limit to one of either Specials or Assists for Staff-users? Seraphic Artes, as you have it now, feels like a powercreeped version that combined two effects. Since you've designed Mikleo as an Iceberg-user for the water-element flavoring, I'd suggest Specials-only.
Re: Jade - Fon Slot Seal is just really cool. The only other comment I could add is that Jade is most certainly primarily a Magic-user in Tales of the Abyss, so making him your Lance choice is a bit odd, but I suppose there are a lot less Lancers in Tales than Magic-users, so I can understand wanting to even out the representation there where you can. Blood Pain is a pretty cool translation of that class of weapon from the Tales games, but if you make more of these, I'd be careful about handing out that effect to too many weapons, since I believe literally every Tales character since Symphonia gets a weapon like this? Don't want to oversaturate your hypothetical "Tales of Feh" cast with postgame optional weapons!