The invasion of Abyssinia 1935, was planned as early as 1932 was a war of revenge longed for by Nationalists which Mussolini had planned thoroughly for a wide array of reasons.
Mussolini invaded Abyssinia because there was evidence to suggest that there would be no intervention by other countries.
Mussolini knew that British and French policy makers would not want to drive Mussolini into the arms of Hitler.
Britain and France did not want to do anything to affect the Stress Front of 1935 which was an agreement to guard against the Nazi threat.
He knew they were not completely against Mussolini gaining an empire in Africa, as long as he did not cause too much trouble in doing so as the British and French also had many colonies in Africa.
Mussolini knew oil would be excluded from the economic sanctions, and oil was the one item that might have forced Mussolini to see the economic sanctions as a serious issue. Germany Japan and the USA were all also out of the League of Nations so trade could be continued with them.
Similarly to the economic “battles” and fascist social changes, the invasion of Abyssinia was a means of propaganda to turn Italy into a nation of loyal fascist so that Mussolini had a totalitarian regime.
He wanted to achieve some of his prestige related Foreign Policy aims:
Need for Mussolini to prove himself.
Create a Fascist Ideology.
Opportunity to make speeches such as speech in Rome October 2nd-“Black shirts of the revolution!”
Part of the Cult of Il Duce. Mussolini restoring Italian prestige of Ancient Rome by expanding the empire.
Regain popularity with the Italian people by diverting their attention from problems at home: economic and race laws.