i saw a video about making different writing utensils, the guy used horsehar, a stick, and glue made from animal hide. tip frayed. rest down?

What we think is irrelevant. Contact the person who made the video and ask them. OR, try your idea and see if it works.

Asking strangers to guess, is still guessing. You can guess as well as we can.

I winder if bamboo pens, also used in Asian calligraphy, would be easier to use. at least for a novice.

The point of using horse hair is that it is stiff enough to hold shape, rather than spreading under pressure.

Wrapping sinew as you described adds nothing, you could simply have used shorter horse hairs.