The Ivorians are their nation's first representative in a continental final since 1995 and will take a lead to Cairo after a spirited showing in Abidjan.
Christian Kouame's first-half penalty was cancelled out by Trezeguet just before the hour, but Roger Assale stepped up in the final 10 minutes to give Sewe something to defend.
Sewe came from behind when the sides drew 1-1 in Abidjan in the competition's group stages, yet they seized the initiative on this occasion midway through the opening period, Kouame converting from 12 yards after Al Ahly goalkeeper Ahmed Adel had fouled Assale.
Assale drew two saves from the Egyptian keeper in quick succession after the break, while Kouame struck the woodwork, and Adel's resistance was rewarded as Trezeguet led a counter-attack which he finished neatly from 20 yards.
However, Sewe stuck to their guns and Assale bundled home in the 83rd minute to give his side an aggregate lead.
A repeat of Al Ahly's 1-0 win at home in July will be enough for the current CAF Champions League holders to win the continent's secondary competition, but Sewe's spirit will inspire them as they head to the Egyptian capital.
