But back to Western Swordsmanship, I've been observing and I noticed that most of the strikes are either vertical or diagonal
Fernando,
When you say "vertical or diagonal" I assume you are referring to strikes that are made from above (
oberhau) rather than below (
unterhau). If so, I wanted to remark on why you don't see
unterhau too often in videos.
First of all, oberhau are naturally more powerful than
unterhau, and a swordsman will naturally tend to utilize
oberhau because they are instinctive strikes, so
unterhau are not the primary form of strike that one faces. Also, the middle strikes (made horizontally) known as
mittelhau are not as strong as
oberhau, nor are they as instinctual as
oberhau, probably because the motion is not quite as natural.
Secondly, in a fight, your most likely to face
oberhau, so it's useful to demonstrate voids, closing, and counters against these strikes. Also, due to the nature of
oberhau, a maximal number of different counterattacks can be applied against them, so they tend to be the focus of most of the historical manuals on the longsword.
That having been said, there is information on dealing with
unterhau, and thrusts, and
mittelhau. However, instructions on dealing with the
oberhau take precedence due to how commonly they are employed and how many counters can be applied against them.