Huge Part Weld To Player Issue Any Fix To The Issue?

When I weld a part that is bigger than the player to the players hand on an R15 rig the player bounces around I am guessing because its too big? The part is in its own model inside the player is there any way to fix this issue?

I used this script to weld the part to the player:

function Weld(Weldx, Weldy)
    local weld = Instance.new("Weld", Weldx) 
    weld.Part0 = Weldx
    weld.Part1 = Weldy
    weld.C1 = Weldy.CFrame:toObjectSpace(Weldx.CFrame)
    weld.Name = "Weld"
end
Weld(Part, RightHand)