Sherem orchestrates a public confession. While we do not know what happened to Sherem while he was in his smitten state, the experience of Alma the Younger later suggests that it was a time when his sins were made clear to him. It is probable that like Alma, he was given the chance to repent. This public confession is very likely the required penitence from God to assist in purging his soul.
Sherem first acknowledges that he taught falsely. This both serves as personal confession, but also as redemption of Jacob. Sherem had been sent to reduce Jacob's influence, and he ends by reaffirming Jacob's position as a prophet. The Lord has taken a negative and made it a strength for the people.
Sherem also notes the power of the Holy Ghost and the ministering of angels. This most certainly pertains to his experiences in the days when he was under the influence of the spirit. Again, an appeal to Alma the Younger's experience suggests that this ministering of angels was for the purpose of Sherem's salvation. Part of his experience clearly showed him both sides of the path to God, salvation and damnation, and highlighted his previous walk on the road to personal damnation. Using the ministering of angels as our clue, this is Sherem's expiatory act as part of the salvation for his own soul.