Shields are the actual problem here. They should cost an action to equip or unequip instead of having zero drawbacks and an exploit to get that +2 AC even if you're using a Heavy Crossbow or Greataxe.
This would also make two handed weapons indirectly more versatile. You could switch quickly between Greatsword and Longbow but using a Shield would limit you to quickly switching to one handed thrown weapons.
Other than Shields I'm fine with changing equipped weapons for free.
