Since you're not saying that a Ninja Sword and a Ninjato are different things per se I'm wondering what your point is. Are you saying that every item in existance only has one correct name? Are you saying that nouns should not be translated into any other language but that of their origin? Are you saying that descriptive terms should never be used under penalty of death? Are you just boasting about your knowledge of this part of japanese culture and looking for a way in which your knowledge of ninja weapons can elevate you above us, the common mortal who dare use the term "throwing star"?
Look; words are not concrete. A Ninja Sword is exactly the same thing as a Ninjato. A Throwing Star is the same thing as a Shuriken. The terms are recognisable as meaning the item they are meant to and there is no problem. Getting yourself concerned with these pedantics is exactly as pointless as me noting that you incorrectly used a comma after the word "sword" in your original post.
But hey, if you still want to use it as a validation of your own superiority, (yes, I am aware that I say this as some twat who calls himself Superior Mind,) then more power to you.