I explained her a bit earlier, but basically she Batteries on all her abilities, and specializes in very long generic buffs. Downside is they can be pushed off easy and don't work well with characters that already self-buff with generic Atk and Max Brv buffs. But otherwise, she is a solid support, and maxed out, her EX+ can deal a solid bit of damage, make enemies weak to her main element of light, and enable one use of a Very powerful Hp+ called Double Holy.
I'd say she's a solid support option, especially since she can extend buffs by one turn using her buffing ability, which means certain characters like Vayne (unique two turn buff gives him Free Turns) and Rem (one turn buff gives her a free ability use, extend it and she gets TWO) can be made much more powerful in a more abstract way.
At the end of the day, you already have her, so consider this Infographic to help you build a team with her!
I'd YOLO max her out, she's rad and she is a solid addition to a lot of powerful parties.
Edit: also, somebody put up a screen shot of how Weapon Skins will work, and it's very disappointing to me personally.
So, I always knew we were gonna have them tied to Weapon Passives, so anything 3* or below is already unlocked, and anything 4* and above is unlocked by fully maxing that weapon and gaining it's passive.
...unfortunately, this only counts for weapons
Who's Passives are Directly Usable by the Character.,
so, what this means is, you can't equip Sephiroth's 15cp to all the Greatsword users, or give Setzer the Death Tarot EX from Ace, or let the sword users use cool Rapiers from Alisaie.
It's just whichever weapon that character is directly linked to that is more your style.
Which makes this whole thing, while very appreciated, practically worthless to me. I would have settled with just 15cp Skins becoming universal if they get mastered, hell, even 4* skins. This is literally for those who wanna use the buster sword on cloud or who doesn't like the look of the EX weapons.
I hope this is just an interim step and they will figure out a way to allow for cross-character Weapon Skins eventually if demand kicks in, because clearly however they needed to program it came with some massive concessions, and it'll probably be very difficult to get it done without sufficient prodding.
Regardless, it's super rad we got it in the first place, and I really appreciate the team's hard work in committing to fan input. It's not exactly what I'd hoped for, but it is amazing and appreciated nonetheless!