Get a piece of phenolic or lexan . .something that's not going to waterlog, some waterproof paper in grits as fine as you want to go, & a bottle of Windex.
Cut waterproof paper in strips the width of the block.
Mount the blade in your vise clamped by C clamp to a piece of 2x2 or 2x3.
Wrap the paper strip over the block.(a rubber cushion on the block. ie. a strip of truck inner tube helps.)
Spray the blade w/ Windex
Work the paper in single direction strokes from the ricasso to the point.
Start crosswise on the blade finishing up w/ lengthwise strokes.
Keep an eye on the blade to make sure the scratches from the heavier grits are being removed before changing to lighter grits.
Polishing a blade can easily take as much time as making the entire blade itself.
If it's a working blade I wouldn't take it to much more than 600 to 800 grit.
Any finer & it will show the marks from use.
Patience is operative the word here!!!!!
Larry