I must've leveled up too much in FFVI...I always crushed Kefka. Exdeath, on the other hand..
The general rule of thumb is, if you pick up all of the optional characters in any Final Fantasy, you're ready to move on to the boss. They also have done a great job of gating all of the bosses with appropriate lieutenants; if you can take the lieutenant, you have shot at winning against the boss.
But back to this problem, because I don't want to derail from straightening out striking the AI homeworld, I think what would fix the wrath lance are one or more of the following:
1) distance from the Wrath lance should affect the damage; it doesn't matter whether far or close, just pick one so there is some tactical decision-making.
2) Wrath lance does decreasing damage to successive targets
3) Wrath lance is weak to one of the triangle ships, including its attack
4) fun idea: The Wrath Lance has orbiting drones that are targetable, allowing the destruction of one arm of the lance. Turning on auto-kiting would make this interesting.