The way that the Melee/Range resistance Permanent Upgrades and Body / Tactical / Heavy Armour works (details here) makes them pretty much useless at higher levels in the Tournament / Endless events. The damage by enemy hits scales up so quickly that the protection offered by the Resistances and the Armour is negligible
Ideas to balance things a bit:
- Make Melee / Ranged Resistance a percentage protection than a fixed amount - e.g. Level 20 Melee Resistance takes 20% off any Melee Damage (see also this suggestion to combine Melee & Ranged Resistance and introduce a Dodge Chance upgrade)
- Compound the armour with this - either additive (e.g. 20% Melee Resistance with 10% body armour gives 30% melee resistance) or multiplicative (20% melee resistance and 10% body armour combine as 1.2 * 1.1 = 1.32 to give 32% resistance).
Heavy armour / Titan protection could continue to give multiplicative benefits like they currently do