Perhaps the understated violence also pertains to what Tobe was going through while living in Miss Emily's home? I'm sure he was tortured knowing that she was sleeping with this man's body...many of the slaves in America were plagued with superstitions and religious practices that would have made Tobe extremely uncomfortable...perhaps why he took off so quickly after his mistress went to meet her maker?
Yes, there is understated violence in the story due to Miss Emily apparently murdering Homer Barron. Since Faulkner doesn't use Emily's point of view, we are unable to read about what happened in the house when Homer died. I'm still convinced that Tobe had something to do with it, too LOL! He was loyal to Miss Emily and most likely had to help her carry Homer's body up to the attic, etc. The fact that the story is told from the townspeople's point of view adds to the mystery of the death of Homer Barron.
The "understated violence" would be the murder of Emily's lover Homer who was not the marrying kind. Emily killed Homer with rat poison (he was a rat to her) why we are not completely certain. However, we may assume he was planning to leave Emily; she had to make sure he would stay forever. After she poisons Homer, she keeps his body in a bed upstairs; when the townspeople find his body they notice a long gray hair on the pillow. Emily has kept her lover and laid beside him in the final hours of his life and finally his death. This image is beyond gruesome. First, Emily killed Homer using rat poison, and then she lay beside him after his death and decay possibly in an embrace as his dead skeleton arms suggested. This violence is understated because the murder is not described. It is Emily's ability to lay next to her dead and decaying lover that is most certainly horrifing.