The deuteragonist of the game, Scarlet, wears an eyepatch. However, the reason why is never revealed, and she explicitly states she doesn’t want to tell you.
If I remember correctly, it’s heavily implied that Vex can and will torture Uproar victims for his own pleasure. In the Center of Craftworld, many can be seen running around in terror, restrained using machines, and generally suffering.
There is a fake-out death scene at the end that is slightly emotional, but the character doesn’t actually die and the cutscene ends on a much happier note.
It is implied Scarlet is watching the player throughout the game, and directly confirmed she is during boss fights and Knitted Knight Trials, but this is more to observe the player's skills and learning than for any malevolent reason.
At the beginning of the game, Scarlet states that even your own imagination contributes to the Imagisphere. At the end of the final level, there is an image of Sackboy waving bye with a caption around the lines of "See you next time, Dreamer!"
It’s not known where Scarlet and Gerald currently live, but they are never portrayed as homeless within the game, and Scarlet was shown to have grown up in Loom in the bonus comic "The Gathering Storm".
While no onscreen cannibalism occurs, Vex threatens to eat the player on multiple occasions. It can be assumed he’s not a Sackperson, but both are sapient creatures, so I’d say it still counts.
The player can choose to equip sword cosmetics to their character, and there’s a boomerang powerup called the Whiritool that cuts vine-like objects and can therefore be implied to cut enemies. However, no graphic cutting occurs.