As long as you're using them correctly, Haarko knives are perfectly safe! Just keep in mind that the blades are sharp, so make sure to handle them with care and always keep them away from your fingers and body.

Oh, and please don't try to chisel, ice pick, pry, apply force to the back of the blade, or make contact with the blades - that could lead to injury. And if your Haarko knife is damaged or the blade is loose, it's best not to use it. 

In terms of technique, try to avoid rocking motions and use swift downward chops instead. And when you're all done, be sure to store your knife safely out of reach of children.