Help with welding 2 parts together, CFrame of 2 parts doesn't stay the same

[Rokquo]

Hey, I’m trying to weld 2 parts together. The 2 parts are:

1. A part that has been welded to the character’s right arm (Small pink part, see images)
2. The handle of a sword (all other parts of the sword are welded to this part too)

The issue is that the weld only works for some swords, not all of them. For example:
Working sword:

Not working sword:

Code: (for both swords)

sword = game.ReplicatedStorage.Assets.Weapons[weaponName]:Clone()
sword.Parent = char
weld = rightArm:FindFirstChild("Weld") or Instance.new("Weld", rightArm)
weld.Part0 = char["Right Arm"].Handle
weld.Part1 = sword.Handle
weld.C0 = CFrame.new(0,0,0)

Sword models: (selected part = handle) (not mine)