A ruler, IMO. Those changes could encourage people to submit to the Crystal Throne, and would encourage Imperials to keep supporting the new Empire. After all, this is the Empire that will lead the world to TG according to prophecy and all that. As we see, this has worked. The Seanchan are totally dedicated to the Empire, and confident in its role at TG. I think it's part of the Wheel's weaving of the Pattern. The Wheel needed the Seanchan to blindly trust their mission and the Return.

Ishamael likes to aggrandize his role and would like everyone to believe he's set everything in motion, but I think that by influencing Artur to send huge armies to Seanchan and Shara while his own forces were stuck at TV for decades, his goal wasn't to set stuff in motion that would play out a thousand years from now but more pragmatically to weaken the Empire on the main continent so that it didn't last and fell when he got rid of Artur. What Ishamael didn't want was for Luthair to step in and the Paendrag line to keep the Westlands united as an Empire until TG.

To alter the prophecies that way, Ishamael would have had to have foreknowledge that Luthair would conquer Seanchan and set up an Empire there, and that it would last. If it wasn't for the a'dam, Luthair fighting against channellers would have met the fate of the Shara expedition (it got crushed), and I'm quite sure this is what Ishamael expected for Luthair.

Of course, he boasts otherwise. He likes his foes to think he reads the Pattern and pulls all the strings. But it's basically crap.