Complex sentence: Protocol III lists certain munition types like smoke shells, which even if they contain White Phosphorus, only has a secondary incendiary effect, and these munition types are not considered to be Incendiary weapons.
Split into simpler sentences: Protocol III lists certain munition types like smoke shells which, even if they contain White Phosphorus, only have a secondary incendiary effect. These munition types are not considered to be Incendiary weapons.