First I’ll state maybe I’m misusing the term client side, all I mean to say is that no numbers are apparent from the players perspective.
So say for example you complete challenge X and loot a pink axe.
The axe on server side has the potential to roll stats similar to the diablo loot system (affixes/ranges varying per drop) but none of this is apparent to the player(outside of aesthetic variation giving hint to traits), certain weapons have stronger baselines and if there’s an affix in the name / visual traits on the weapon then the item can be assumed to having such traits. So if it glows with fire, it probably does something with fire, if it has a cool looking grip maybe it has a decreased fatigue modifier.
Sure when you loot the axe you could go out killing boars and collecting data, but in the case of things like belts or boots, noticing that they decrease your movement on certain terrain, reduce your jump distance, reduced endurance, but again with no numerical transparency creating a sense of testing / exploring content after receiving items to understand what its good/best for.