Hello, I need some advice on cleaning.

I recently picked up a couple stright razors, both at antique shops. One really nice silver metal handle, a Cluass Shear Co, and the second a Black plastic engraved handle, H. Boker & Co. a Keen Shaver model. I picked up the Keen for the purpose of sharpening practice, and it looked pretty cool (not being a plain flat handle).

With the Keen, I wanted to clean it up, and the handle as I mentioned was engraved/molded with a vines type design, there seemed to be a fair bit of grit and dirt embedded in this design. Thinking at the same time to disenfect the balde I used a mixture of Hot water with some vinager to start the cleaning process. The problem from this is that doing so has turned the black handle brown (discolored). Is there any way to correct this?

With the Clauss blade, this is more of a polishing question. I picked up some metal polish (which worked great on the blade) however on the metal handle it keeps coming up black. What I mean by that is that the instructions say to rub / polish until the black film disapears. So I add the polish, rub it in, wipe off the black, give it a rinse, then repeat (as this was my first time polishing it). However, the second and even third application was just as black as the first. Being that this is my first time doing a full clean and polish, I'd just like to know if that is normal? That regardless of the number of times I use the polish it will always come off black? I had thought that the black indicated tarnish.

Sorry for the wordiness, just wanted to be clear.
Any insight would be great.
Thanks