The Blood Sword will be unavailable, unless the player gave it to Ricard before he died.
Starfall XVI targets the whole party, and hits for moderate damage. The Emperor uses Flare XVI frequently, alternating between this and his Starfall XVI attack. The Emperor may sometimes cast Holy XVI or Blaze XVI on the whole party. The Emperor repeatedly casts Dispel XVI attempting to remove their buffs. The Emperor's regular attacks hit for high damage and also heal himself.
If the player gave the Blood Sword to Ricard in the main game, the fight against the Emperor will be a simple affair. 16 hits at most will eliminate the Emperor. Dual-wielding it with Ricard's Wyvern Lance or Scott's Wild Rose will ensure maximum accuracy.
Otherwise, the party should be bolstered with buffs such as Haste, Blink, and Berserk. If Scott's Wild Rose has been obtained, it can be used to cast Berserk XVI on the entire party. As the Emperor does not use many status effects, Shell and Barrier are not necessary.
The Emperor's offense comes primarily from his magical attacks, of which only Blaze XVI can be mitigated. Thus, it is important to have a high amount of HP for all party members and to have Minwu and/or Scott heal as necessary. Using the Ancient Sword to inflict Curse will make the fight much easier, as the party will inflict greater damage to the Emperor and receive reduced damage from his attacks.