So I am making a calculator for Ranger, but I came across an interesting note.
"Weapon Lv. 4 - Every +1 upgrade gives 7 ATK, 0~14 ATK for every Over Upgrade pass the +4 safety limit, and 12 ATK for every High Upgrade pass +15."
So I was testing figures and noticed that variance from upgrading is not being added to my damage.
It can be hard to test this through normal hits, but critical hits use max variance. My crit variance never changes in spite of using a +13 BxB in this instance.
A guildmember tested variance on a +12 FQL on one of his characters, and variance applied then.
So I am thinking that over upgraded bows, at the very least on Archer classes do not apply this.