If there is a movement that is more derided and made fun of than any other then surely it must be x-block. I have lost count of the number of time I have seen, in person and on the internet, an instructor throwing his hands up in a mock X-block against a knife attack. This is usually accompanied with a loud theatrical kihap. Over time I feel that this one movement has become a representation of all traditional martial arts and their ineffectiveness. I have my own feelings about instructors that openly make fun of other styles for the purpose of making their style look superior but that is for another article.
The x-block is found in a number of different traditional arts. If you go with the idea that the patterns or forms were created by fighters then X-block has stood the test of time and was preserved in the forms for a reason. It is the modern interpretation of the movement that it wrong.
Even if you take a training partner and practice some short range striking and grappling you will find that there are times that your hands will naturally cross. Maybe in order to clear arms, get to the outside, strip a grab. All are applications of the different forms of X-block that can be found in patterns.
If for example we look at the rising X-block as it is found in Jhoong Gun. A high attack causes us to throw our arms up in defense, in the case of Jhoong Gun this would be our right arms. We then slip our left arm up in front of our right arm, and between our right arm and the attackers arm. The next movement is then to step round and at the same time turn the attacker away from us. The following movements are to secure the arm and counter attack to a target that is presented.
It is quite difficult to write down an application of a movement but I hope you follow it. This is just one example of an X-block application based on a natural motion or reaction. As I mentioned before there are many more, for example
Toi Gye, Stripping a grab from your wrist that has been seized in response to you trying to execute a throw.
Gae Beuk, Stepping back and catching a shove or double handed grab, before stopping the attacker with a kick.
I hope that these few examples lead you to start looking at X-block in a different light. It is much more that a useless relic but a very effective and natural motion for close combat It is deserving of in depth study.