If you can find an appraiser/sword specialist,have them look at it.
They can tell you all kinds of things from the halmarks etc. they can also advise you on the best way to care for and store your treasure.
If it was a katana I'd suggest just coating it with clove oil,but thats likely very different steel and the handle jewelery is totally different and may need it's own care and handleing.
I totally understand,the no money part but again if it was mine I'd get an expert to look at and help me preserve it.
Most these type of swords arent really worth alot of money,relatively,{some swords can be worth millions}That said the sentimental value can be priceless so you owe it to yourself to preserve it the best way possible.
PS: I think it looks great just the way it is!