You can summon gallows and nooses, there is a quest in the Wild West area where a bandit is hanged off-screen, clouds cover the noose right before he gets hanged and he’s gone when they vanish.
Objects with the "Suicidal" adjective will seek out weapons and deplete their own health, but the act itself is not graphic. They will lose the "Suicidal" adjective if given the "Friendly" adjective.
Mental illness is portrayed as either jumping all over the place erratically or becoming a serial killer. There’s no other portrayal possible within the game.