This 1929 Treaty was of mutual benefit to both parties with the Vatican getting recognized as its own independent entity- and the not-so-subtle 'understanding' that since it owed its very existence to him, the Vatican was not only to recognize Italy and Mussolini as its undisputed Head of Government but also was NOT to criticize anything Mussolini or his Allies did.
IMO, no doubt the Invasion of Ethiopia, the Libyan Concentration Camps on Mussolini's part [and, of course, the Holocaust on Hitler's part] were given Papal blind eyes [at least] due to this treaty so I'm wondering if there may have been some kind of moral or ethical protests on the Popes' parts re the above atrocities and others had Mussolini NOT recognized the Vatican's sovereignty over its decidedly reduced territory. I recognize that there WERE individual priests, nuns and other Catholic clergy who DID resist, protest and protect persecuted folks at the risk of their lives and freedom during that timeframe but it seems they did so on their own initiatives rather than due to enacting official policy. Still, I wonder if the lack of a treaty would have made a difference.