How do i make a variable for the player who damages the NPC with a tool??

When a player equips a tool, the tool get's transferred to the player's character in workspace. So i thought this would work:

humanoid.Parent.Head.Touched:connect(function(otherpart)
if otherpart.Name == "Handle" then
    local character = otherpart.Parent.Parent
local player = character:GetPlayerFromCharacter(character)
print(character.Name)

I basically have a sword as a tool in the backpack. Otherpart.Parent.Parent would be the player's character, since the tool got transferred inside the player's character in workspace.

Why does Roblox Studio give this error?

GetPlayerFromCharacter is not a valid member of Model