"Fire Emblem Engage (NSP)(Update 1.3.0).part2.rar" is a split RAR archive containing the 1.3.0 patch for the Nintendo Switch game, which adds "Expansion Pass Wave 3" content. This file, found on third-party sites for emulation or custom firmware, requires all associated parts and 7-Zip or WinRAR to extract the functional .nsp update file.