I would not bother with polish cream. It makes me think of the Grow "it" big creams that I know nothing about at all.
If you want to have a bash at it, I recommend a regime of uchiko cleaning. I am doing this with an old wakizashi that I have that would not survie another polish.
What I do is I clean the out-of-polish blade with uchiko once a month as if I were cleaning the blade as directed by the NBTHK guidelines. I take of the oil and apply uchiko and give the sword about 20 wipes on bothside, very lightly and evenly and then give the kissaki a slight once or twice over. I take care not to put finger pressure on ridges and crisp lines as uchiko will take these away. Hamon and the like should start to come out. The only think it is a very slow process and it may take years to really see anything. What you should do is take photos of before and compare them monthly (or bi annually) to see how things are going.....