Fast Cast at this point in the game on RDM specific gear is an insult. Capping is extremely easy and even easier at the su5 required to wield the sword. Please pick any other weapon's ending buff that isn't job specific and just slap it on that sword, please please please.

Refresh +3
20% enhancing magic duration
5% damage taken to mp
Treasure hunter +3 (why not!)
3% of HP to attack or defense
Crit rate 10
20 spell interrupt
15 attack per shadow (still better than 20 fc!)
20 snapshot (yes i have a bow, flurry 2, distract 3, and +55 gain agi and i know how to use it)
10 damage taken
-40 tp step cost

All of these are worth more to me than a little bit of recasts. I would trade it for the 50 ranged accuracy it's missing as well. You managed to put ranged accuracy on BRD?, DNC?, THF, NIN but left it off SAM who has a RELIC BOW and RDM that actually has the ability to use ranged WSs unlike BRD and DNC who do not! We are on volte gear, raetic bangle, taeon, exalted bow, and raetic bow. You can use arching arrow off exalted bow to get innundation bonus and the fusion we so desperately need. Support us!

ALSO every mage gets more magic damage or magic accuracy than RDM does. 310 for the staves, 248 for the clubs and even though blue mage shares our 217 they get 20 blue magic skill. We got the least good mage weapon no matter how you look at it.

It doesn't matter how the aug system works out or makes this a better weapon later, you're still doing us dirty now and it will still be there later. Please at least consider this for future updates if you aren't willing to fix this weapon.