Effective Felicia Build?

Felicia's best job is as a mage tank. This much is obvious, you take the magical hits and kill with glacies. Having poison dagger doesn't do much because of her low attack. Going for the chip/debuff route could work, but you really need the phantom spd seal or maybe darting blow if your running windsweep. This means, if you have phantom spd, the only chip you will be doing is from the savage blow c skill. Rouge dagger with windsweep doesn't work due to rouge dagger increasing you defenses, and windsweep being a player phase skill. If you do the windsweep smoke dagger build, it can work very well and with darting blow, you can still do the chip damage with double savage blow.. There are other units who can do it better however.

Here's mine with the same IVs,

Full Build:
Weapon: Smoke Dagger (Def or Res) / Rogue Dagger (Spd or Def) / Poison Dagger / Kitty Paddle (wishlist) / Kagami Mochi (wishlist)
Assist: Reposition / Draw Back / Dual Rally
Special: Iceberg / Glacies
A-Slot: Fury / Distant Defence
B-Slot: Cancel Affinity / Guard / Windsweep / Quick-Reposte (yet to give)
C-Slot: Savage Blow / Ploy / Buff / Flexible
Sacred Seal: Distant Defence (single best Seal for Felicia) / Attack Ploy / Savage Blow

Summary/Notes:
*Personally I think debuffing is a secondary gimmick and is definitely not unique to Felicia, so I think you should focus on her high Res and mage killing potential.
*Icerberg over Glacies after the dagger buffs because, one she has enough Attack and Speed to deal damage now, and two she can kill Reinhardt with Iceberg on the bait. If Kagami Mochi is ran, Glacies can be taken to accomplish the same job.
*Fury and Distant Defence actually lets her tank Mulagir Brave Lyn (Fury prevents double and DD helps her survive) and either kills her next turn or destroys her with QR.
*QR is completely viable with her high Speed because it guarantees doubles against fast ranged units, namely mages (who can easily hit 40+ Speed) and Brave Lyn.
*Kitty Paddle and Poison Dagger are actually great due to her Speed (50+ Attack / 43-47 Speed against Infantry is basically Ayra or Mia's spread) but Refinable Smoke and Rogue are more valuable in my opinion.
*Defence Ploy should be taken with Kitty or Poison Dagger.
*And finally, I just want to add some points to what CDexCD said, being that Windsweep does actually synergize with Rogue Dagger because it lets her set up for the enemy phase. The buffs from Rogue Dagger do not actually transfer from enemy phase to player phase (bait to engage), only player to enemy phase (engage to bait). Also, Phantom Speed is definitely not needed if she has 43-47 Speed. The downside to Windsweep is actually the fact that it ruins her players phase by canceling her doubles, hence halving her damage and decreasing her Iceberg/Glacies charge time.

Hope this helps.