I proposed a better system some time ago, and now with the new 'alerts' system, I believe potential for player feedback with this feature is possible.
Basically, a lot of twohanded weapons have a 'wield' state that you enable by activating the item which switches the mob sprite and in some cases ups the damage. In other cases, you can't even use the item without wielding it (defib paddles).
I propose a new system of hand restrictions that goes as follows:
Twohanded-mandatory items: You must have two free hands to hold a super-heavy item (Gibtonite, heavy parts) or you can't pick it up. This is the most simple style of heavy objects and will be standardized for other large items with better feedback.
Twohanded-optional items: A heavy item that can be held with one hand will be in a 'debuffed' state if your other hand isn't empty.
Bad concept art:

Essentially, everything will work the same, except there will be a check for your offhand when picking up a twohanded-optional item, that will buff it and change the mob sprite if your offhand is free. The fireaxe does more damage when wielded, so it will do more damage and have an alternate mob sprite if your offhand is free.
Defib paddles will be automatically useable if your other hand is free, rather than having to wield them.
Two-handed rifles (assault rifles, grenade launchers, LMGS) will be usable with one hand, but you will experience recoil when shooting them and possible shot deviation.
Large guns (miniguns, etc) that are too heavy to even aim will require both hands to carry or you won't be able to shoot it. Essentially, you'd be able to carry it with one hand using the carry handle or under your arm, but since both hands won't be holding it up, no hand would be on the trigger.
You'd still be able to pump shotguns with one hand like the terminator, don't worry.