My opinions are Saki (ranged melee with fast attack speed and ranged assassinate), Solano (cheaper mage but can only attack during skill, AW ability speeds up attacking), Claudia (True Damage upon Skill AW, this one's long term since you have Imelia, Sherry and Kerry for duelists already AW), Despara (attack speed up on a high attack, slow-inflicting unit is great), Shuka as you don't have Uzume (team-wide attack boosting skill, reduce deployment costs is helpful even if it's not what it was once hyped to be and she's essentially a cheaper, weaker samurai for fighting) and Yuyu (cheaper alternative to Despara, she has Platinum level attack for Gold -1 cost and Range Up is helpful in some maps, like War of Magic)

Priority Order IMO:
Despara > Solano > Saki > Shuka > Yuyu > Claudia

Reasoning: the first three are already in position to be AW given their max level status and you're lacking in magic damage (which is why Saki is 3rd as ranged melee isn't needed as often as magic damage); with Despara AW, Yuyu shifts down a slot below Shuka (Shuka's AW's only benefit besides making her a stronger fighter is an extra -1 to deployment cost of any units deployed after her while she's still out), with Claudia last due to your duelists being adequate and her biggest draw (Skill AW) not yet implemented.

Ertel is an option for melee slot heal, and Rita is a long-term investment like Claudia (except she's niche in usage). Bashira's AW bonus is iffy but she's an option since she IS stronger than Rita as an archer, but I might take Rachel instead for ranged physical damage.