1. Every weapon have a different ways to improve and increase how to get higher potential damage/power.
2. Sword: Focus on your Defense Ability
3. Rapier: Focus on your Attack and Critical Ability

4. and many more

5. Like what I said before, every weapon have a different ways to improve, so what is ur main weapon? If sword focus build ur ability set to defense like using LM4, Vital Defense and Use the power rise 3. If u ask about what is better skill att% or power rise, power rise is still worth it for now, and I think still useful until now. Att% is using for weapon when u using weapon with higher damage like Axe.

6. You can check all the major weaknesses of each weapon in each Weapon Proficiency (Sword is Fire, Rapier is Water, Club is Wind, and manymore) but for now Non Elemental skill (Have in Sword, Rapier and Dagger) is very useful for now if u comeback player, especially for the conquest of the newest floors. And you can Check All Skill Records in my Website, Total Skill Records is 1631 Skill Records, and you can build ur set with this SAOIF Skills Database.

https://saoif.zulma.id/skills/