Hello Slamyr,
I was looking over your question and I was able to make a quick example using the couch knights project. I added two sockets to the sword and simply traced a line between them. I hope this information helps.
Example:
Here you can see where I add the two new sockets “Base” and “Tip”
In this image I used two custom events to start and end a loop that fires off a line trace between the two sockets. This effectively follows the blade of the sword but only when attacking. This means that it will continuously fire off a line trace while the attack is happening.
Make it a great day