I mean GoW has RPG Progression, its likely its just levelling up, getting perks.
HOWEVER, I do think this game will have Metroidvania aspects with navigating the world so could tie into that too.
RPG progression systems in non-RPG games is becoming to be a red flag for me with games. I my experience it just means more bloat and running around engaging in collectathons. I prefer the more streamlined gameplay in TLOU Part 2 and Uncharted 4.