Why do players fling when welded to a non-cancollide part?

The code is below.

This function instantiates a block that should expand in one direction. It is welded to a ball. The ball works perfectly by the way. It's just welded to the player.

When this part extends, basically the player goes into a frenzy and flings around a bunch. How do I stop this?

local AttackLine = Instance.new("Part", Character)
            AttackLine.CanCollide = false
            AttackLine.Transparency = 0.5
            AttackLine.BrickColor = BrickColor.new("Teal")
            AttackLine.Name = "AttackLine"

            AttackLine.Size = Vector3.new(0.2,10,0.2)


            local weld = Instance.new("Weld", AttackLine)
            weld.Part0 = AttackLine
            AttackLine.CFrame = Character["RightHand"].CFrame
            weld.Part1 = Character["RightHand"]
            weld.C0 = AttackLine.CFrame:inverse()
            weld.C1 = Character["RightHand"].CFrame:inverse()

            local originalFrame = AttackLine.CFrame

            for i = 0, length, length/10 do
                AttackLine:Resize(Enum.NormalId.Bottom,i*500)--AttackLine.Size:lerp(Vector3.new(0.2,50,0.2), i)
                AttackLine.CanCollide = false
                local weld2 = Instance.new("Weld", AttackLine)
                weld2.Part0 = AttackLine
                AttackLine.CFrame = Character["Chargeball"].CFrame
                weld2.Part1 = Character["Chargeball"]
                weld2.C0 = AttackLine.CFrame:inverse()
                weld2.C1 = Character["Chargeball"].CFrame:inverse()
                wait(0.1)
            end