Max is right -- you don't know the exact composition of "jeweller's rouge". But it's usually ferric oxide.

Whipped Dog uses 0.1 micron FeOxide powder for his "fine" pasted strop, so there's precedent for using FeOxide for sharpening razors.

You could try some jeweller's rouge, and report back here. Even if it's a mistake, it'll be a cheap mistake.

Charles