Weighting ilevel calculations

[Lithera]

You divide by 13, not 12, and items that take up 2 slots get counted twice.

In general, upgrading from ilvl 70 to 90, you will see the biggest stat increases for visible armor > weapon > belt > accessories > shield

13 only if equipping a shield otherwise it's 1 Wep, 5 Main Armor, 1 Belt, and 5 accessories for 12. For tin can or robes you divide by 11. They do not get counted twice. That's beside the point though. The issue is it's just a flat average when as you said you see a much bigger stat increase from the weapon and main armor slots and therefore there's a glaring difference between an i67 character with GC wep, AF gear and a wall of i90 accessories (which may or may not be for their current class)*-, and an i67 character with a bunch of lvl 49 accessories but an i90 wep and myth armor, or even an i67 with a Garuda wep and mostly Darklight.