My cat's cause of death

On the day he died, my cat, Raymond, had fluid drawn from around his lungs to ease his breathing. It worked, but by later that afternoon his breathing problems were bad again and by evening the vet recommended euthanasia, saying that Raymond wouldn't have lasted long and only suffered.
It's common to second guess yourself after doing these things and I have. The fluid was sent out for testing and it turns out Raymond had a sarcoma cancer in his lymphocytes. I'm probably saying that wrong. The main
thing of interest, to me, is that sarcoma is the type of cancer that required amputation of my leg in February of 2018 and is likely to kill me in a couple of years despite that. It often affects the lungs and kills you that way. 
This makes Raymond a harbinger of sorts. 
Initially, I said to have him part of a mass cremation. Early the next day, I changed my mind opted instead to have him cremated solo and his ashes returned to me. Yeah, I know: Ten to one they just scoop out an approximate amount of ashes and say they're of your cat or dog. Nonetheless, I wanted to take him back to his home in some way. This kind of touchy-feely thing is not my way, though I'm polite enough not to judge others.
The pet crematorium put the ashes in a nice little box. It has brass fittings and a small padlock. Why a padlock? My guess is that it keeps kids in the house from opening the box to get a look at their late pet's ashes, an act that will lead to the usual bad things kids do. Spillage. 
My parent's ashes are in cardboard containers in a closet downstairs. My dead cat has it better than my dead parents. Perverse, no?