+HP -Def Young Tiki

You can't go wrong with Breath of fog in her case. Considering she will hardly fill a spot in your arena core, you might as well make her useful as a melee duelist and a dragon killer, since especially dragon killers can make your time in AA relatively easier.

You don't even have to refine her weapon if you don't want to and you can give her fury, which goes well together with her weapon's renewal effect. The rest can be whatever you want - quick reposte for enemy phase focus (recommended) or swordbreaker to dominate a certain matchup (also useful especially in AA, but be careful with falchions tho). I kind of like her AoE special, because it has huge range so you might want to keep it or go for moonbow/glimmer (glimmer is better against low res melee targets/mages and dragons thanks to effective damage). C sklil is flexible and depends on the rest of your build, but you can't go wrong with something like drive speed. Sacred seal can also be whatever you want. Reciprocal aid might also be a good idea with her increased hp pool and it will allow you to fully heal her allies and heal herself afterwards thanks to renewal from her weapon.