With the introduction of the magic system and the fact that you introduced the durability system and the fact that you can improve that durability, I say that we should create "Enchanting" and also add greater damage per slice effects to a sword, Or make it slice faster at the place where you improve the durability.
I will only go into enchanting because the other thing is simple and not so hard to understand, Anyway, Say you have a sword and you want to enchant it, You need a tome for the enchantment you want, Mana and a weapon of course, Improving enchantments could use either a "Mana Crystal" which allows for more mana that the weapon can support, Or to improve the statistic of an enchantment you just simply buy a crystal for whatever magic the enchantment uses, whether it is fire or light.
Now, When you swing it, And it hits, You loose the mana that the enchantment requires to have its effect upon hitting a person, So it's Enchantment Cost x Swings, This mana can regenerate, By a 20% max if you skip your turn and it depends on how many rush counts you give away, 10 rush counts equals 10%.
Now, There's also a max amount of enchantments a sword can carry, depending on it's rarity, I will explain these to you in PM if you think this suggestion is a good idea.
I will show you an example of the template for this modified sword,
|The Unholy Destructor|
|50%+ Speed, 50%+ Damage|
I can expand on my idea if you so request.
To go into specifics, Weapon Modifications, Done at the repair shop, Basically gain you normal stat increases, Like 70% damage or 50% more speed. They will simply cost normal money, Enchantments however would require a level, a crystal corresponding to the type of enchantment (Dark, Fire, Whatever, if it's an enchantment that is in both types then it might require two, Depending on how strong the enchantment is it might require two or more of the same crystal.), It will also require a tome for the enchantment, And mana of course.
The regeneration of mana on the weapon will simply take mana from you, Though there may be enchantments like "Manaburn" that gives some back upon slicing.