Currently there's no progression system in the game, and players lack specialization in any shape or form, meaning they lack identity.
Here's my suggestion for how we can implement this once illuvial combat is introduced:
Defeating an illuvial should not only grant XP to the illuvial fighting alongside the ranger but also to the ranger, while providing expertise to the weapon used.
Rangers would be able to level up to 100, with each level increasing their stats by 1%. This is very important to differentiate new players from experienced players and help scale the region's stage difficulty. (New players should have a hard time going to a stage 3 region).
To ensure that gameplay feels meaningful, players should need to use a weapon consistently and gain expertise with it to unlock its full potential.
Each weapon type would have its own skill tree, which would unlock abilities and stat boosts. With this we would greatly increase the weapon's versatility, giving players the option to customize their weapons.