Thoughts on this Celica build...?

that's pretty standard build.
just put brazen on SS, then you got the standard triple brazen build.

Meanwhile the +Speed have got a better perform, your build suits perfectly to Oneshot so many heroes with the brazen actives (and without them).

Just invest right now into the Brazen SS and try to play arround her % of activation.

BTW: 10 hp are so perfect to build arden sacrifice in her support skill (but take care about any hp buff (for example with any future merge), in that case you can't use the arden sacrifice to active the 75% brazens).
Otherwhise, you are gonna lose 5 HP with raganaroks first engage and you need to lose 5 hp more to active the brazens...

Take care about the special, blazing ligth is just not worth (glimmer or moonbow can be paired well with flashing blade as her SS... but thats a better option to a +speed Celica).

Celica works best with fury imo. It allows her to get more kos when shes not in brazen range as well as easier set up. Giving up a 69/53 offensive statline for a 65/49 is acceptable imo.

And her best seal slot is heavy blade (paired with a 2 turn special). Maybe even QR in order to set up and get kos against ranged units in enemy phase but only if you dont have any other DC or ranged baiters

Maybe change her special to Glimmer since AoE specials dont consider in-combat buffs. Other than that, standart but good. Also congrats on her perfect IV's.

Maybe consider the brazen atk/res for her c skill

For what I have played with her, if you want to run a double brazen build with Celica, make it with fury-desperation + weapon brazen + seal brazen. That way, you reach brazen and desperation range in one attack and helps a lot her survaibility.

You should really only double brazen if you know what you’re doing and can get her into that percent via reciprocal aid or ardent service etc. Fury is better to run to stay more consistent