Use them? What do you mean, ‘Use them?!’

HEMA pioneer John Clements once expressed the opinion that sword-makers could not learn to fight with swords because they needed to spend all of their time and energy on their craft. With all due respect to John I disagree; I feel that a sword-maker must be familiar with the use of swords in order to make them correctly.
Don’t get me wrong, I don’t think the sword-maker needs anywhere near the skill that a highly trained martial artist does. But they do need to be familiar with the basics, with cutting with swords and a host of use-related aspects of the sword.
On of the oldest and most respected modern sword companies makes some swords that work very well and others that don’t work at all. Why? Well, for one thing they concern themselves mainly with a sword’s appearance. More importantly they have no basis to determine if a sword ‘works’ because they don’t use them. Ever. So when they make a sword that does work it’s more-or-less a ‘happy accident.’
In a way this goes back to what I found when I first seriously tried to study swords; that you can’t just study swords, you need to study everything. The technology of a given period will influence what they can do to make a sword perform correctly; a sword made from poor materials needs to be made differently than one made from top-quality materials to minimize the chance of it failing in use. The social context of the sword may influence it’s design in that a sword meant to be worn with ‘civilian clothes’ may have different requirements than one meant for the field of battle. The cost of swords in a given place and time, trade, Guild Laws, laws concerning who may or may not own swords, the materials available to them… all of these things and more are involved in the design of a sword.
The thing is it’s easy to look at a book and say, “This sort of sword generally had a narrow handle.” If you know how the sword is meant to be used then you know why they tend to have narrow handles. You can know that a sword used for armored combat needs to be rigid, but experience with thrusting and the methods used to employ the sword you will know how rigid it has to be.
The typical reaction of a modern fencer handling a sword is that it’s too tip-heavy. But a person that knows the techniques for using the sword knows that it’s tip heavy for a reason, and it feels ‘right’ to them.
There’s no such thing as ‘too much knowledge’ when it comes to a craft. A knowledge of the way things are used will inform the way that you make those things and as a consequence you will make them better.