your copper shield json "extends" your wood shield, inside i found this error:
wood_shield, line 17, translation y should be 2
wood_shield, line 22, translation y should be -2
wood_shield_blocking, line 17, translation y should be 5
wood_shield_blocking, line 22, translation y should be 5
i'm not sure if this values cause the error but you can change them and test again