Kaze

When fully built up, Kaze can be the mage killer and Vantage abuser that you've ways needed in your life.

His base Resistance (34) is pretty high with Fury only boosting it further. Kaze's res is good enough to survive a few mage and retaliate hard, if the Kaze is -Hp it's fair to say an attack from a mage and fury will bring him just about the line where he can abuse Fury and Flashing Blade. If the team is using Infantry Flash, you can easily remove Flashing Blade with Spd Smoke making him an anti-mage, special sweeper, AND debuffer.

For a normal team, Kaze would generally perform better with Iceberg instead of Glacies. However, on my infantry team I happen to run Infantry Pulse and Infantry Flash, making it so he can basically fire off a Glacies or two even in a quick match. Now that I'm thinking about it you could have him +Res or refine resistance for his weapon to make Glacies do more damage, but from what I have experimented, he still kills and survives most of what you would put him up against. It's honestly your choice whether to focus res or speed, but since I run Infantry Flash I've got to make use of it, plus I like seeing the 50 Speed on the character profile (summoner support and merge +3 spd).

Kaze enters the fight as another magus killer, true to his nature in Fates. He practically shares an identical stat spread to Felicia, but due to his boosted BST for a dagger unit he has an attack stat to work with, being 30 which is rather decent for his class. Boasting great speed and resistance one can optimize to increase his offense while also keeping his mage tanking capability, using both Life and Death 3 and Fortress Res seal.

Kaze can be interpreted as a variation on Felicia who hits significantly harder but who doesn't have a 14-mt weapon with adaptive damage. In order to establish his niche in contrast to that of Felicia's, he can make use of the excellent weapon that he comes with.

Since he cannot pick on melee units for dumping their res, he will need to hit significantly harder, especially in the current meta, which likes to bulk up on def. Having 7 points more atk than Felicia from IVs is a good start, and a +atk IV continues in the same direction. (+spd is also a good IV for this build.) Brazen atk/spd is the ideal skill to maximize offensive power, with one critical challenge: activating the skill, along with desperation, so that no DC unit will be able to target his weak def. Here we utilize a strategy that has long been used by Felicia: baiting squishy mages.

On Felicia, QR is a reliable option because mages can push their spd into the upper 40s or even low 50s without merges using just a little team support. This build can function well with the QR seal, aiming to go with this same strategy. However, thanks to his higher atk, Kaze can opt instead for another seal which interests far fewer units and take out his mage opponent in one shot with a glimmer activation. If the mage has 39 HP (which is unusually high), Kaze's 45 atk will OHKO them up to 19 def, which is sufficient against very squishy mages. However, if they have invested in their def to survive a single counterattack from a DC unit, they may have enough bulk to survive, which is where def ploy comes in. Mages cannot invest simultaneously in spd, def, and res; if they invest in def to survive a DC strike, they will need to sacrifice some res, and 34 is almost invariably enough to ploy them; if they keep both enough def to survive and enough res to prevent the ploy, they are probably the Julia/Deidre/Micaiah type and Kaze will simply outspeed them and double naturally. (If for any reason you don't like def ploy, an atk+3 seal has similar effects but is less powerful and cannot support the rest of the team.)

Now that Kaze has downed his first opponent, he enters brazen/desperation mode and has 53/45 offensive stats, 58/50 effective on any opponent he ploys. Glimmer will activate on every engagement unless they use guard. Assuming the ploys land, the maximum def+HP combinations that he will be able to KO without buffs or merges are:
42 def + 40 HP
41 def + 42 HP
40 def + 45 HP
39 def + 47 HP
38 def + 50 HP
37 def + 52 HP

As such, this build has potential to blast through even some of the dragons and armours that are commonly seen in the current meta, especially if Kaze receives an atk buff. Ayra and Karla are also easy targets for his ploys, though he may still need a spd buff to double them.

The units Kaze may struggle the most against are TA+raven mages, who will bring his attack down into the 30s using weapon triangle advantage and inflict heavy damage on him by inflating their own atk stats into the 60s or even 70s in the process. These need to be left to teammates, probably those who have colour advantage, since TA is a double-edged sword. Opponents with vantage active are also safe from Kaze unless they are melee units without DC, since he will not be able to survive the pre-emptive strike. Two unique units who can resist this build are Selena and Fir due to their high spd and res, preventing doubles and ploys. Brave Ike and the rare users of deflect missile will also survive, though they most likely will not counter. One last counter to this build is the uncommon hardy bearing seal on a DC unit, since Kaze most likely will not OHKO them and would fall on the counterattack.

As a final footnote, Kaze generally cannot bait nearly any build of Reinhardt, including those utilizing atk+ seals instead of quickened moonbow. The man hits very hard, and this build is designed to withstand one hit only. Kaze can win against Reinhardt by initiating the fight himself; he will double and win easily even if he does not land any ploy on Reinhardt. Have a teammate throw him forward with a reposition, and off he goes.

This build was designed to turn Kaze into a heavy debuffer. This attack smoke 6 effect debuffs a total of 14 attack points from anyone unlucky enough to be caught in his range, which is devastating, especially in an arena scenario. Of course, you can use any Smoke skill you wish in seal slot, in order to weaken enemies in other ways, depending on your overall team compostion.

Being a free unit, I wasted no time building the free dagger unit Kaze. With his great Spd and Res, there's no way I couldn't NOT put Swift Stance on him. With the Res they gave him, he is undoubtedly supposed to be an anti-mage unit. So I put the Kitty Paddle on him along with B Tome Breaker since it's the Tome with the most threatening magic users. With Swift Stance boosting his already good Res and Spd, and the Kitty Paddle doing its work, he is undoubtedly one of the best solutions for a threatening mage. Rallies and invisible buffs like the ones Marth's Refined Falchion gives also help him a lot. Reinhardt, Guntharra, Miciaiah, Julius, Nino, and many more don't have anything on him if they don't run Daggerbreaker (which they usually don't).
I'm really proud of how I built Kaze. I needed a different dagger user since the Halloween Sakura I sacrificed had a Atk bane, making her utility with the Kitty Paddle pretty limited as she had less of a chance to one shot mages. But Kaze came in and stole the show, certainly living up to his name as retainer.