Although I am not even a member, it should honestly be a long term-perm banning.
A Death Threat, and encouragement for someone to commit self harm is not something you should take lightly, so I am not sure why you think it is something that should be built up.But if they do end up being a built up punishment. The user being threatened can just call the cops, asuming the player lives in the U.S.
"Death threats are annoying in the extreme, but try not to let them ruin your life. As we’ve discussed, most are simply hollow words meant to upset, annoy and harass you. Don’t fall for the tactic."Lucibella, Rich. 'Knights Armament SR15-E3 Carbine | SWAT Magazine'. Swatmag.com. N.p., 2012. Web. 7 July 2015.
Also fix the black list so asuming can be as-suming and not assuming