For neutral weapons they must be unclassed(neut) sailors. Early weapons only need basic ability which all
sailors have. Some neutral ships can have national weapons - most often it is depth charges. In that case
you must have a sailor of that nation. A while ago, neutral sailors became no longer able to man basic
national weapons such as low torp/dc.

Only level 12 and under national guns and launchers can be loaded onto neutral ships. USN does have a set of torpedoes that work well on neutral ships but they dont fit on the DDMP. Just level a neutral sailor up abit in order to use the neutral equipment. Stats wont matter unless you plan on BVEing it.