Hi hi, Crypt of the NecroDancer has a very difficult combat mechanic to implement to RPG Maker if you're not mastered at eventing. I don't know about the other parts but for Weapon Damage, you can create a common event that check if current equipped weapon of player has name X, then when press attack, it'll create a Dynamic Event with notetag <dmg: skill name in database> or something else. This gives you more control than using Weapon Slot 1/2, but of course, it depends on what you want to achieve that decide whether the eventing will be complex or simple.