is there a way to do this without moving the character?

hello, so i am trying to make a script that whenever you unequip a sword(tool) it welds to your back, i found a way to create a clone of the tool but when i try to move the CFrame of that clone (so i can make it go on the players back) the player moves to that swords new CFrame (https://gyazo.com/c0a118b444861c619be5944f56f6dc6f the player moves to the sword)

Full Script:

local onback = false
local UIS = game:GetService("UserInputService")

function BackWeld() --item must be in inventory
	if not onback then
		local player = script.Parent.Parent.Parent.Parent
		local char = player.Character
		local upperT = char.UpperTorso
		
		local toolclone = script.Parent.Parent:Clone()
		toolclone.Parent = game.Lighting.OnbackFolder
		toolclone.Name = 'OnbackClone'
		local clonechildren = toolclone:GetChildren()
		
		local model = Instance.new('Model',char)
		model.Name = 'SwordForBack'

		for i = 1 , #clonechildren do
			if clonechildren[i].ClassName == 'Part' or clonechildren[i].ClassName == 'MeshPart' then
				local ultraclone = clonechildren[i]
				ultraclone.Name = clonechildren[i].Name
				ultraclone.Parent = model
				ultraclone.CanCollide = false
				
				if clonechildren[i].Name == 'Handle' then
					for i,v in pairs(model:GetChildren()) do
						if v:IsA('MeshPart','Part') then
							local Weld = Instance.new('Weld', model)
							Weld.C0 = model.Handle.CFrame:inverse() * v.CFrame
							Weld.Part0 = model.Handle
							Weld.Part1 = v
						end
					end
				end
			end
		end
		local modelhandle = model.Handle
		
		local backWeld = Instance.new('Weld', modelhandle)
		backWeld.Name = 'Backweld'
		backWeld.Part0 = upperT
		backWeld.Part1 = modelhandle
		
		modelhandle.CFrame = upperT.CFrame + Vector3.new(10,0,10)
	end
end

script.Parent.Parent.Unequipped:Connect(function()
	print('Activated')
	BackWeld()
	wait(1)
end)

the part of the script that i think matters is:

		local modelhandle = model.Handle
		
		local backWeld = Instance.new('Weld', modelhandle)
		backWeld.Name = 'Backweld'
		backWeld.Part0 = upperT
		backWeld.Part1 = modelhandle
		
		modelhandle.CFrame = upperT.CFrame + Vector3.new(10,0,10)

because i think this is because i need to use a different weld but a weld constraint also doesn't work so whenever i move the 'modelhandle.CFrame' the player moves with it

if anything is unclear comment i'll try and explain it better

not sure if this will work but maybe try change

local modelhandle = model.Handle

local backWeld = Instance.new('Weld', modelhandle)
backWeld.Name = 'Backweld'
backWeld.Part0 = upperT
backWeld.Part1 = modelhandle

modelhandle.CFrame = upperT.CFrame + Vector3.new(10,0,10)

to

local modelhandle = model.Handle

local backWeld = Instance.new("Weld")
backWeld.Paren = modelhandle
backWeld.Name = "Backweld"
backWeld.Part0 = upperT
backWeld.Part1 = modelhandle

modelhandle.CFrame = upperT.CFrame + Vector3.new(10,0,10)

what i did here was first just creating the weld and then parenting it, the rest was urs, btw when u set names of something new use " instead of ', same thing when u make an Instance.new

after i started looking at free models of people doing this i found out i was doing the wrong thing, this is the fixed part if anyone in the future has the same issue:

local modelhandle = model.Handle

local backWeld = Instance.new("Weld",modelhandle)
backWeld.Name = "Backweld"
backWeld.Part0 = upperT
backWeld.Part1 = modelhandle
backWeld.C0 = CFrame.new(1,1.5,0.6)
backWeld.C0 = backWeld.C0 * CFrame.fromEulerAnglesXYZ(math.rad(-90),math.rad(300),0)