I am looking for a new holster, too. I have a canvas one which can fit a 2" chisle, if only I could remember where I got it. I store my chisle in it. I usually wear a 1.5 inch chisle at raisings. You certainly need to be aware of your tools and surroundings while climbing, but there is no more risk of a chisle falling out of a holster than a hammer; be careful.

Jim

The closer you look the more you see.
"Heavy timber framing is not a lost art" Fred Hodgson, 1909