21 inches to hit them with the blade perpendicular to me. Yes, I can initiate a grapple from that same distance, but it's not an effective grapple, more of just a grab. Besides, sticking my arm out with no weapon to guard it is asking to be maimed. A modern drive step would be very hard in heavy armor. A medieval single handed sword may be pointy at the end, but something that heavy is not a serious thrusting weapon. A short sword is a thrusting weapon, and so is a dagger, but a two and a half to three and a half pound weapon is awkward for a during combat thrust. It's better used to finish someone on the ground. The answer to your last question is that given a choice I would avoid using one handed weapons against a person in full plate if at all possible. if I had to use one I would use a mace since it has the crushing power to hurt him through the armor. Then I might use a wrap shot, but not with a sword unless I knew very well what I was doing. If I had to use a sword it would be a great sword. Preferably I would use a high powered crossbow with an armor piercing tip, or early gunpowder weapons. The problem with this conversation is that by the time you have seriously good plate, it's 1400. The era of the knight is starting to die off. All that awesome plate coming out of Milan is being created during the early renaissance. Most of what SCA heavy fighting is simulating is early middle ages combat. Many of the manuals also come out once printing is cheaper, i.e. the renaissance. German sources are an exception, but many of them are still later.