I mostly use 50HF spring steel (US 6150). The hardness depends on the intended use. Sharp swords have a higher hardness, e.g. 55 HRC, which translates to the blade dulling slower. The training swords are softer and more elastic. The intended use also determines the type of cut and the thickness of the cutting edge  – usually the blade is around 6 mm at the grip and 3 mm at the point As it should be in accordance with swordsmithing practice, the fuller ends under the crossguard.