Alright, is she really that much stronger than the game's other mages?
More, she gets an earlier start than the other mages at the same level. She's almost broken in the beginning until some of the other mages can catch up. But if you manage to max her out she does have some of the highest damage output out of most others.
Alright, is she really that much stronger than the game's other mages?
Lysithea is a min max character. She has terrible growths in pretty much everything except the ones that matter ie magic, dexterity, and speed. Even someone like Annette is fairly slow whereas Lysithea will double nearly all enemies, hit them hard for each attack, and even land a good number of critical hits thanks to her dexterity. Her passive ability mastermind also doubles her skill growth experience from combat, meaning she's going to master her skills and get access to her entire spell list the fastest.
Her spell list itself, though relatively short ranged, is quite versatile in the damage she does. From her Reason skills, Swarm debuffs, Luna ignores a certain amount of resistance, Dark spikes does insane damage to cavalry units (RIP Death Knight), and Hades is the most powerful reason spell in the game. Her faith skill tree gives her access to Warp, which has incredible utility, Seraphim, which is great against the many demonic beasts you end up fighting at the second half of the game, and Abraxas the strongest faith spell in the game.
Her biggest weakness is that she has low range, all her spells are 1-2 range, and that she's about as sturdy as a wet tissue. She's a glass cannon that can obliterate anything but pretty gets screwed by anything that can sneeze in her direction. If you position her well though she can do a lot of damage to the enemy.
Additionally giving her Thyrus is like giving Thanos the fifth stone for the Infinity Gauntlet, it just completes her. The 2+ range it gives her, in addition to the extra 1+ range she gets from mastering Reason, pretty much means she's nuking enemies from very far away and gets rid of her range weakness. The staff also has a chance at reducing the damage she takes by half which makes helps make her less fragile.
Pretty much every speed runner uses her because of how much damage potential she has and how quickly she reaches that damage potential. Evening on maddening difficulty she's still fully capable of nuking that pesky Death Knight.