Null reference when equipping left hand

[qdwazar]

Hello. I have a weird issue. I set up a new handler item manager than i can equip a weapon for both hands than. After some time cannot really pintpoint what changes because i did not modify any of those scripts. It breakes and gives me a null ref error but it is out of my league to pinpoint what exactly the problem is.

[Invector]

So at first you can equip the weapon in the handler but after some time it stops working? 
It shouldn't work in the first place if something is wrong... check your ItemManager EquipPoint tab to see if the handler is correctly assign