I have found it impossible to bend these tips back without breaking them unless I first soften the steel a little bit with a torch. A short time in a gas fire or hot charcoal will to the trick too. Just bend back with a pliers after you've softened it. You are then faced with the matter of re-hardening the tip appropriately. I am not going to engage in any metalurgical speculations here.
Experimentation is fun, however, and remember some steels are easier to re-treat than others.
Place them on the ground and place the knife, bow-up , on them. The bricks should be far enough apart that the last inch or two of both the tip and handle ends of the knife rest upon them. In general, you want to place the center of the bowed part right in the middle of the opening. Now apply weight to the center of the bow by standing on it. Do this slowly, and do not apply much weight without stopping and checking your work.