Here is some code you can use to add an Accessory to a humanoid locally:
function weldAttachments(attach1, attach2)
local weld = Instance.new("Weld")
weld.Part0 = attach1.Parent
weld.Part1 = attach2.Parent
weld.C0 = attach1.CFrame
weld.C1 = attach2.CFrame
weld.Parent = attach1.Parent
return weld
end
-- Check the thread to get the rest of the code