Having removed a few katana blades in the past, I thought I would share my methods, right or wrong, born from experience and even a few cuts to the hand.

In order to remove the tsuka / grip, I believe it is best the blade points up and you gently tap on the guard / tsuba with something fairly heavy but with a rubber cover, like the handle / grips of a pair of fairly hefty pliers.

First, remove the katana's Mekugi / peg from the tsuka / handle. This is a little wooden peg that holds the blade in the sword. It has a slightly larger and a slightly smaller end. You need to gently tap it out from the smaller end side. Use something round, flat and about the same size as the peg to avoid breaking / splintering it. It may come out easily, it may not. If not, the blade may be tight against in relation to the grip, so try taping the end / pommel of the grip (sometimes called the "butt cap") on the floor to see if this eases the blade's hold on the mekugi peg. Of course, save the peg once it comes out.

If the mekugi is in a bad way, many people say you can replace it with a section / length of chopstick. I actually find the wood used in chopsticks to be weak, of poor quality, and would actually recommend the wooden shaft of a small paint brush; as pain brushes can come with hardwood shafts, they are very much ideal.

Next, remove any saya / scabbard, then find something to firmly hold the blade while protecting both it (from the natural acid oils in your hand) and your hand of course. A sharp blade is a problem, an issue. So be aware of how sharp the blade is first. Never hold the blade directly. If the blade is very sharp, you should perhaps place a small length of wood between the cutting edge and your hand. Otherwise some paper cloth / towel should be fine with care; you are only going to grip the blade enough to hold it in the air.

Next, go around the tsuba / guard gently taping with the rubberized instrument, a small rubber mallet would be ideal. Tap around the tsuba again and and again until the tsuka / handle comes free. If it does not come free, the blade may have corroded inside the handle. If so, you will need to stand the sword blade up for a while and apply some form of break free lubricating oil where you can, so it slowly runs / moves down the tang into the handle. Normally overnight should be fine. And then try tap, tap, tapping again.

Slowly but surely is the first golden rule. The second rule is to save the guard fittings (seppa, tsuba and fuchi) in the correct order for when you need to put your katanas back together again.