Yet another saint link. St. Jerome is a patron saint against anger - no small surprise there as his vehement temper was reknown. THere msut be others, but as discussed elsewhere, doing a search on anger brings up amny saints known to have bad temprs, and little about who to pray to help us with ours.
Could also try praying to patron saints of peace, such as Francics of Assisi, Barnabas, and Elisabeth of Hungary. Gabriel the archangel is the patron saint of diplomacy. I couldn’t find any one under serenity.
Youa re probably already aware of this, but the way that siants are some tiems assoicated with their cuases, or Patronages has much to fdo with how their devotees lobby the Holy See. There are many saints who are known for remarkable restriant under trying times; like Faustina, Mximilian of Kolbe, or any martyr. Just because they are not officially recognized by the Church as being a patron of a cause does not mean that we can not ask them to pray for us for issues that trouble us; issues that they are knwon well to have navigated as a role model.