Here's some example slots and item sizes:
Size 4: carry only (Lances, two handed polearms)
Size 3: Back (2 slots) (single handed spears, shields, two handed weapons, javelins, large bows and crossbows)
Size 2: Belt (2 slots) (Single handed swords, bucklers, quivers, small bows, throwing axes)
Size 1: Concealeable (4 slots - stuffed into boots and/or a bandolier (pistols, bullets, throwing knives, rocks, slings, daggers)
Using all the slots would be very bad in terms of encumberance. Walking around with 3 pistols, a sword, a crossbow, a shield, bullets and a quiver would be every bit as silly as it sounds.