You got the same results I have been struggling with. It is difficult to get both the point and the flat right. My best brisket was a flat only on my Weber charcoal kettle.
I also had trouble slicing the flat. The meat would stick to my Global chef knife and crumble. I also had to slice the meat in half because my knife was not long enough.
I did some research on meat slicing knives and discovered that this is a common problem. It seemed most BBQ folks I would see were using these knifes with round ends.
I wanted to understand what that was all about.
I bought a Dalstrong slicing knife which has been great. It is sharp, long, and meat does not stick to it. I am able to make clean, thin slices.
The granton edge reduces the surface area contacting the meat, reducing shredding and tearing.
I have not yet had the chance to try it on a brisket, but it has performed well on turkey breast and tri-tip. I just did a turkey breast this week and it did great making thin, sandwich ready slices.