Average item Lv Formula?

[Hitome]

shield not counted in ilvl btw

u may have shield equipped

Wrong.

It seems that accessories have less weight than main body gear.

Wrong.

Apperantly, your body gear have a higher standing then your acessory gear.

Wrong

I'm sure different items have different weights. Switching from i70 to i90 body usually gives me 2 average ilvls. Switching rings from an i49 to i90 only gave 3 to my average though

Nope they do not.

2 handed weapons count as 2 slots and 2x the level, and level rounds down.

Im a summoner. No Shields and Im using a Crimson Circlet, soo no Cowl. Lets see 12 Slots Total.
Crimson Lv80
Darklight Tome 55 (110)
Vanya Robe 70
Darklights x 7
Austere tights 60
Demagogue Ring 60
Total 815 (870) / 12 (13) = 67.9 (66.15)
Game says item Avg Lv 66

Oh look: someone who can do basic math.