I had a similar problem (sort of) with my geldings mane, it needed to be shortened but was too thin to pull it and be able to braid it. So what I dd was:
I took scissors and first I cut it to about a little longer than where I wanted it. Then I took the scissors and cut vertically up and down the mane to sort of "muss" it up and look a bit more natural. It looked great!!! It is possible to shorten manes with scissors if you go slowly and don't cut too much at a time!! Good luck!! :)
Basically the exact same thing a hair stylist does to a human to give "layers" to hair.
I do that all the time on my horses with just a plain ol'. It makes the cut look natural, and not blunt. It's quick and it's easy.