Great mystery box pull! Is it just one red led or is it three red leds? Just wondering if they gave you tri-cree since it seemed very bright on camera.
The two screws you are referring to are not for blade retention, they are to hold the claw shroud in place and be able to rotate the claw to the desired position to line it up however you want. The blade retention screw is actually under the silver emitter holder. So you have to unscrew the emitter completely in order to access the actual blade retention screw and it is just one screw not two. I believe what you are doing now is screwing the two screws for the claw shroud so tight that they squeeze the blade in place, which is not the intended design for them and likely why your blade flies out.
Also a couple suggestions to stop rattling. First on a reaper with no sound the rattling is coming from both the battery pack and the led. Once you get sound on your reaper, the rattling of the battery pack goes away because the added speaker makes everything nice and snug. Without sound, I recommend getting a non-vented pommel and putting a little bit of tissue or cotton below the battery pack to stop that rattling. For the led rattling, when installing the blade, carefully make sure it goes down far enough to hold the led in place. This is a little tricky because of the silver emitter holder. It is often best to put everthing together without the retention screw and mark where the blade first contacts the led. Then afterwards tighten the retention screw with the blade in to where you marked. This is kind of a pain but once you got it marked, you will know how far the blade needs to go to keep the led snug to stop rattling but not too tight to push on it needlessly.
A lot of good information here but you are wrong about the two screws he is taking about. He is talking about the two screws below the claw and on each side of it. True they do not hold the blade, but they are also not for the claw. I think you are referring to an older style. I'm adding a picture of what he is talking about.