I almost gave up rage because they would open in my quiver. This is how I fixed my problem and never had one open again.
Buy a bag of dental retainer bands($3.29) they are small and strong but cut easily take two toothpicks and spread the band wide as you need to clear the top blade and down half way on the rage there is enough tension to keep the blades closed and when impact happens it cuts the bands and does what it was intended to do.
This picture is of a #120 boar hit square in the shield with the rage, it didn't get a pass through but cut the heart almost into.