Why would you drop Duelist's Chapeau for this? First, it does not add a Refresh effect. Second, it does not surpass the Chapeau for Enfeebles that are Black Magic based (Gravity, Bind, etc).
Its usefulness is debatable for things like Paralyze and Slow if dMND is not capped; however, Estoqueur's Chappel +2 offers the same amount of MND with slightly less magic accuracy (7 accuracy versus 11 skill). If dMND is capped, then D. Chapeau +1 would be the superior choice. Based on the above, I wouldn't be jumping to obtain this, especially considering the recent update that made AF3+1/+2 even easier to obtain.
But the argument is moot. Very few monsters actually resist enfeebles that they are not immune to or have a coded 95% resist rate to.
There is an important additional aspect of magic skill: interruption rate. Spell interruption rate goes down with higher skill, and up with the attacker's level and damage amount. Magic accuracy does not do this, only skill.
This is why in the old 75 game, well-geared red mages (enfeebling 345ish) could reliably sleepga several Dynamis mobs that were attacking them at the same time, while black or white mages had a much harder time doing this.
Now with hard hitting delve mobs and Adoulin mobs in general that are tough or higher at 99, it is once again useful to equip the highest possible enfeebling skill for sleep, bind, break, gravity to minimize interruption.
Duelist's Chapeau +2 still wins in this respect for RDM, but for the other mage jobs, Hyksos Khat +1 is the best option, even beating Fea's Coronal slightly if for the purpose of minimizing interruption rate we only look at enfeebling skill and not macc.
