Plus there is a level of social expectation. People have an idea of what some things are and where they are from. If you call a weapon a katana you're looking at an asian culture, sword would, by many people, be associated with european/UK cultures.

I once wanted to use an obscure middle eastern bladed weapon in a story and was asked to change it to sword. I ended up describing it as 'sword like', but it made my teeth hurt.