Yes Izzy, the steel is in the same condition as it was. The lighting effect has changed but can be restored. It's probably tarnished and scratched upsetting the former finish which, at one time, caused the hamon to be more visible.
I would start with a passive approach by using a paste on a make up pad. You can buy those in quantity at the make up section.
Just rub Semichrome or flitz compound on it in as even coverage as you can and see what happens. If that does not achieve the desired result, you may have to use very fine sand paper, then the compound. It should come back to where you can see it.
If you have to use the sand paper, please refer back here first or contact me. It's important to know how to hold the knife and which way to apply the sanding.