Complex sentence: Mutakkil-Nusku himself died in the same year (1133 BC) leaving a third brother Ashur-resh-ishi I (1133--1116 BC) the throne.
Split into simpler sentences: Mutakkil-Nusku himself died in the same year (1133 BC). A third brother, Ashur-resh-ishi I (1133--1116 BC) took the throne.