The higher priority ones are the Cassis Crista attributes for:
Enhanced Rodelero Shield Attack
Enhanced Hoplite Shield Attack
Repeated Hits Attack Boost
Then, basically any copyable skill you mainly use:
Shield Bash: Enhance
Shooting Star: Enhance
Synchro Thrusting: Enhance
Kunai: Enhance
Then I guess some fillers:
Targe Smash: Enhance
Headbutt: Enhance
Shield Shoving: Enhance
Scutum Hit: Enhance
After solidifying a good number of core skills you can branch to Peltasta skills:
Enhanced Peltasta Shield Attack
Umbo Blow
Rim Blow
You can reach for them in whatever order you like, but of course take all the passives (that you need) first like the strike debuffs, Synchro Thrust: Pierce, and Targe Smash: Frozen Stone, Remove Knockback.
You can ignore Evade Thrust: Bleed cause its not as cost efficient
Also, this is probably the most expensive class attribute-wise in the game, but you don’t have to go too far to get really good damage.