I wish it were true, Kwai.
I don't use ceramic glass beads - those do give a nice finish, but are finicky, slow-going and expensive.
I use 120grit silcon carbide beads.
The best way to think of it would be this:
Imagine you and, say, 10,000 of your friends each bought a ballpeen hammer and covered the ball end with 120 grit paper. And then I turned you all loose on a giant sheet of steel as big as a warehouse floor...to beat the crap out of it.
If I only leave you for a few minutes, I would just end up with a bunch of random dents in the steel floor. But if I left you all there for a few days...eventually I would end up with a million little dents in the floor and the surface would be very uniform. Bumpy, but uniform.
That's what bead-blasting does. It hits the steel and "micro-dents" it, turning it in to a "bumpy" surface that no longer reflects light but scatters it.
Bead-blasting actually makes a knife more likely to rust....because it leaves it with a 120 grit finish, and many more places for moisture to stick to (a la surface tension).
Polishing is the best rust-prevention...and works better with steels that have more chromium in them.
Dan
