This is unfortunate. Cutting yourself with your sword is akin to shooting yourself in the foot with your own gun. Would you trust a gun instructor who'd do that ?
Sharp swords – also called Live Blade or Shinken in Japanese – were designed to kill people swiftly and effortlessly. The only reason to use them is to practice Tameshigiri – actual cutting of targets. This is done in a particular environment, with strict safely guidelines.
They should not be used for Iaido which is normally practiced with Iaito. Iaito have the same geometry and shape than regular katana, they may be slightly lighter to prevent stress injury, and they are dull to avoid accident. They are designed for this purpose of safe practice.
If Japanese masters use them, so should you.
For the following 3 reasons :
A dangerous fallacy.
I have heard many people say “I like to practice with a sharp sword, because it forces me to be more accurate.” Invariably, those people cut themselves. And it's just a matter of time before someone cuts someone else. So this is a fallacy, and a dangerous one.
A bad image of Yoshukai
Unless you know what you are doing, you will cut yourself, as long as it happens in private, it is your problem, but if it happens in public, you are displaying a poor image of Yoshukai in front of students or parents.
A serious liability
An other aspect of this is that when you bring to a room, a dojo or a beach a sharp sword and leave it unattended on the ground, you are in effect letting a dangerous weapon in the open for anyone to mess with. Would you leave a loaded gun laying on an open table in a picnic area ?People, and children in particular, are curious and can be sneaky. If anyone would grab your sword and accidentally cut themselves, or wound or kill someone, you would likely be liable, as would probably be whoever organized the event or own the venue where it happened.
So if you don't have a sword, please purchase a Iaito, there are some good ones available at Cheness. If you already have a sharp sword, dull it. Use a grinder and take the sharp edge out of it or ask someone to do it for you. If you want to keep your sharp sword purchase a Iaito.
If you have questions about sword purchasing, please contact me at Frederic.firstname.lastname@example.org