Viktoria, I used golden armor and siren esper to upgrade slash resistance ..
because the base missile resistance is already high, so I don't think it needs to be buffed
Use Passive HP up and Self sacrifice for PvP
Self sacrifice and thief lore for PvE ( More Agility )
In an arena setting, Viktora has the highest damaging attack in the game (9400) when facing an opponent with 50 Faith, 0 Def, 0 Res. She doesn't have Def Pierce, but is an incredible unit nevertheless.
If you make Vik slightly slower then what ever you are countering her jumps will be consistent in pvp. There is a patch in jp to stop AI using jump if target turn comes before jump CT. I had very good results leaving her at 81 agi to counter gunners in high end arena. If you got a decent Ice Lance you really don't need self sacrifice to 1 shot gunners.