Depends on how realistic they want it, if Str is the measure and then one back pack with 5 small pouches and 2 big ones, 3 scabbards and a purse, and possibly a shield is probably all you can carry. Small items being stackable, or each pouch accepting X number of pounds
If you want to make it cool have a 30 pouch inventory and that should be separate from equipment that is equipped, loot gets dynamically distributed and similar light items (one pound or less of the same loot type) stack automatically. Size does not matter you can carry a Pike in one inventory slot or a Kite shield.
Weight:
Realistic, you lose agility the heavier the pouch gets.
Cool, you can carry at normal speed = to your weight, heavier, you move slower.