Knife Hand Block
This is a technique which is found in many martial art styles, there might be a few differences but the technique is the same. On this video, you will see how to properly do a knife hand block, by Sang H. Kim.
The knife hand block is also known as the hand sword, one of the advantages of this block is that your hand is ready to grab after blocking. The main purpose would be to stop the attack and then have an option like grabbing the wrist to follow up with a counter attack.