My problem is extremely simple, I want to have a Combat hit spell perk that ONLY applies on left attack or a Mod attack damage perk that ONLY affects weapon in the Right hand. Unfortunately , it seems like it is impossible to detect which hand is attacking unless I heavily mod the Attack data for every single humanoid race in the game (which will create huge incompatibility issue). The other, safer way, is to have an Onhit script that detects AkSource but I'd rather avoid scripting if possible.

What happens if you use a PerkEntryPoint (I assume you are for Combat Hit Spell and MAD, so...) with a Condition of "GetIsUsedItemEquipType"? You can set that for Left or Right Hand, so it might do what you want? Not tried it, so it might not work, but it seems like a possibility?

Seems like that doesn't work, because even if the weapon is equipped in Left or Right hand, it's Equiptype is still BothHands

Hmm, and the wiki says it's obsolete, anyway... :/

According to the Wiki, 'GetEquipped' as a condition does not work for items in the LeftHand; I wonder if you could somehow utilize that at least for the MAD in the right-hand?

It doesn't look like there's any other conditions for determining Left/Right weapon from what I can see on the wiki...

I already thought of using GetEquipped too to detect if the weapon is in right hand or not, but it unfortunately requires a specific ID instead of using any weapon...