hasWeapon = OffhandHasWeapon()

Return whether a weapon is in the offhand slot.

Returns

hasWeapon 

Flag - 1 if an item of type Weapon is in the offhand slot, nil otherwise

Note: Shields, Held Off-Hand and other non-weapon items in this slot are typically not a weapon. You can think of this return as the equivalent of:

local _,_,id = string.find(GetInventoryItemLink("player",GetInventorySlotInfo("SecondaryHandSlot")) or "","(item:%d+:%d+:%d+:%d+)")
local _,_,_,_,itemType = GetItemInfo(id)
return itemType=="Weapon"