Those look like hard rubber type scales. I've had great success using steam to straighten most materials. If I'm doing a quick clean up, I have a plastic spatula that I put between the scales. I hold on to the tang with one hand and gently pull the spatula away from the pivot side while steaming over a kettle. I've done it many times and can usually get the scales to do whatever I want. Works well enough for most blades. If im doing a full restoration I'll unpin and straighten the scales individually(the right way).
How do they look with the blade closed? Some scales can flex like that when the blade is open due to the shape of the tang and go straight when closed.
