Code:
weapon1:=SWORD_ID
weapon2:=KNIFE_ID
Creatures.ByRange(3)>2 [else]
Self.Inventory.LeftHand()<>!weapon1!
Self.Equip.LeftHand(!weapon1!)
{else}
Creatures.ByRange(3)<=2
Self.Inventory.LeftHand()<>!weapon2!
Self.Equip.LeftHand(!weapon2!)
Please remember to change SWORD_ID and KNIFE_ID.
Good Luck!