When gaining the sword, it is important to not think of it as a bind. This is a subtle action, used to control the opponent’s weapon through superior positioning rather than pressure. We hear from other authors such as Fabris that we shouldn’t allow the blades to touch at all.
L’Ange doesn’t seem to be quite so extreme. He merely says to avoid gaining the sword too strongly, as it would expose the body to much and your opponent, looking for such as advantage, will see the opening.
L’Ange seems to be suggesting that the hand and right foot move at the same time. That is to say, you approach with a “stiff arm”. If so, this would contrast with Agrippa who has you move your arm before your foot.
In any event, L’Agne strongly warns us that the constraint must be complete by the time the left foot lands. Or in other words, you can’t step forward and then try to gain control of the opponent’s weapon.
Note here that he didn’t say “before you move your left foot”. So don’t try to form the constraint with just the right foot, as you would then have to waste a tempo trying to keep it as you pull up your left foot.
L’Ange does say much on where to step, so I’ll share some advice I was given a long time ago. When gaining narrow measure, take a small step away from the sword, no more than the width of the foot. This puts you at a somewhat better angle, granting more control in the constraint.
Then when attacking, take a small step towards the opponent’s sword in order to better expel it from your presence. Again, the step should be no wider than the width of the foot.
Whether or not L’Ange would agree with these minor corrections is unknown to me at this point. However, I find them to be useful.