Abraham had three wives that we know of: Hagar the Egyptian, he (illegally) divorced because God instructed him to do so. Sarah, we know all about. And Keturah, whom he also "sent away" while he was still living (ie divorced). She and her children get no inheritance, much less a blessing, just some gifts and well wishes and off they go (not unlike Hagar).
Note that Ishmael, Abraham's son, came back to bury him even though his mother had been divorced (and he was thereby disinherited). The sons of the concubine(s!) didn't. It's telling that the narrator still calls Ishmael Abraham's son, even though he is not legally. But Keturah's children are not mentioned again (though their genealogy is significant in that Moses goes to the land settled by one of them and there finds his wife).