Japanese Sword Maintenance Guide Part 2: How to maintain your sword
How often your perform maintenance depends on what sort of blade you have and what you use it for. If you have an iaito from Japan that is made from Zinc/Alluminium you do not need to use uchiko powder because it will not rust. If you use it for iaido then you should oil it as and when is needed. However if it is for decoration only then once every two months should be fine.