In higher floors in the castles and tower tournament, the Melee and Ranged resistance Permanent Upgrades are rather useless (see Defense: Resistance, Armour, Perks for more details of how they are applied)
It would be a lot more useful to have a Dodge chance upgrade that increases the built-in dodge chance (similar to how the First Aid upgrade adds on to the built-in 100 + 5% of Loadout Health)
However, rather than increasing the number of permanent upgrades, I suggest to combine the Melee and Damage Resistance upgrades as a single Resistance upgrade and set it to the higher of the two existing attributes (so no one experiences a reduction in resistance) and then allocate the lower value to the new Dodge chance.