Some notes on Dark Falz Loser.
The Apos Dorios and Dark Falz Luther are both weak to Wind and Light based attacks.
*Dorios is vulnerable to Panic, which is a Light based effect that causes enemies to behave erratically and sometimes attack each other. When applied to Dorios, it causes him to be paralyzed and sort of hover in place off-canter.
I would suggest using RaGrantz, dropped from rare version of Quartz Dragon, the Crys Draal, as it has a good power and the infliction isn't the most important thing, the damage can count for more.
*Luther is vulnerable to Mirage, which is a Wind based effect. When Mirage is inflicted to his center 'clock' chestpiece, it will temporarily open up and reveal a weapon point.
I would suggest using Zan, the regular old wind toss, as the rate of inflicting Mirage is also cut by the number of attacks in the magic. A one-hit is more likely to inflict, while something that generates multiple attacks is less likely.
In either boss type, having or Il Grantz, Ra Grantz would prove useful, especially as both of these can be customized for more damage, while the old standard Na Megid is also useful for powering damage, it sort of falls off about halfway through the Luther fight, as he starts moving around much faster and there's no time to charge up before he teleports or throws waves of damage, and the shorter casting time of Il Grantz lets you get off more reliable shots.
For those minmaxing their weapons, having something for Panic + Light Damage, another for Mirage + Wind Damage, and a third for Pure Light Damage, you could change out weapons to handle moods. Panic/Mirage to inflict, then Light to take advantage of the moment of weakness.
Also this:
https://pso2blog.wordpress.com/2014/05/08/the-biggest-luther-dark-falz-loser/