Thank you Carlton Banks,

SIGKILL is often caused by Linux's out-of-memory killer. Linux is saying "I'm out of memory, I'm gonna kill an application that I think is to blame", and in this case it guesses Armory, which is probably the correct one. Running dmesg should show that the "OOM" event. Maybe you can confirm?

The second crash is definitely our fault, but it's hard to tell what's causing it.