I've been holding the weight of my trumpet mainly by gripping the valves with my left index and middle fingers, and with my thumb in its loop on the first valve slide. While this is a pincer grip, I wouldn't call it a "death grip" as it doesn't require too much effort from any individual finger. My left ring finger also usually supports some weight in the third valve slide ring, my right thumb supports some weight under the lead pipe and my right pinky supports some weight in the loop on the lead pipe. I used to support the weight of my trumpet by letting the bell rest directly on my left index finger but I changed to this grip when I noticed a lump forming in my left knuckle from the sustained pressure. Thanks, I'll keep trying.