Zeke

Weapon: Holy Gradivus

Assist: Positional Assist

Special: Sol / Bonfire

Passive A: Atk/Def Catch 4

Passive B: Lull Atk/Def

Passive C: Def/Res Menace / Atk Smoke

Sacred Seal: Atk/Def Solo / Mystic Boost / Atk/Def Form

• Not much else is needed to get Zeke up and running, as the developers gave him a clear and synergistic base kit that works splendidly with his weapon and statline. In particular, Holy Gradivus essentially gets rid of the need to run Quick Riposte or Distant Counter — something other slow and bulky units usually need to do. Thus, this allows him to run: 
  • Atk/Def Catch in the A-slot, which is a great default Attack and Defense augment with pretty easy conditions.
  • ...and Lull Atk/Def in the B-slot, a default skill of which he can ask almost nothing better as it improves both his bulk and damage output while applying a debuff disadvantage on the enemy. 
• With further dual-phase stat boosts from the Sacred Seal (Atk/Def Solo and Atk/Def Form or similar come to mind), Zeke becomes a formidable all-around threat with strong follow-up attacks in both phases, as long as you play with a good brain and keep his HP above 25%. 
• For the most part, Def/Res Menace is a great default to keep given it improves both types of Zeke's great defenses while improving the damage output of himself and potentially other magic-using allies for the Resistance part of the skill. Atk Smoke is cheap and ultimately consistent, though, given it can reduce the Attack of multiple enemies in range rather than one singular unit per turn. 
• To maintain the automatic follow-up conditions of Holy Gradivus, one can opt to run self-sufficient sustain skills such as Sol or Mystic Boost for longer-winded battles. Else, focusing on damage output through stat skills and Bonfire is valid.

Weapon: Holy Gradivus

Assist: Positional Assist

Special: Iceberg / Sol / Noontime

Passive A: Atk/Res Solo / Mirror Stance 3 / Bracing Stance 3 / Atk/Res Unity 

Passive B: Lull Atk/Def

Passive C: Atk Smoke / Def/Res Menace / Pulse Smoke

Sacred Seal: Mirror Stance / Mystic Boost / Fort. Def/Res / Bracing Stance

• Zeke coming with a distant countering weapon in Holy Gradivus and a great base 35 Resistance to go along with it means that Resistance stacking is totally in the cards for him. In particular, superinvestment in Resistance helps Zeke be more properly prepared for a majority of Aether Raids defenses as many top defending units are magic-weilding. 
• Otherwise, the skeleton of the build isn't that different from Zeke's base build; all we're simply doing here is swapping out Atk/Def-based A-slot and Sacred seals for Resistance-based stat swings. 
  • For optimal dual-phase performance in the A-slot, Atk/Res Solo and Atk/Res Unity allow Zeke to gain some nice additional Attack and Resistance when honoring their respective positioning conditions. Mirror Stance 3 or Bracing Stance 3 pushes Zeke into the enemy phase pigeonhole but grants the ever-appreciated Guard effect, making Special charging even slower if not outright impossible for his enemy. Stalling the enemy Special also mostly compensates for his lack of true countermeasures against Null Follow-Up users.
  • Most of what's been said for the A-slot also applies to the Sacred Seal; if Zeke isn't using Mystic Boost as a complementary source of sustain or enemy healer suppression, he should be running a good Atk/Res or Def/Res stat Seal here. 
  • Zeke's higher investment in Resistance makes Iceberg the preferred burst Special over Bonfire now, though Sol (or Noontime with Geirskögul support) are at your call if prioritizing survival. 
• There's still pretty much nothing better than Zeke's default Lull Atk/Def (for lack of options anyway, no thanks to being a cavalry unit), which serves to generally improve his tankiness by debuffing the enemy's power and defense for basically free. 
• For Aether Raids carry play, Zeke will prefer a Smoke style as Menace's single-target behavior won't exactly prepare him against multiple fights in one sitting. Atk Smoke is easily accessible and generally improves Zeke's tankiness further by cutting the enemy's attack power. Pulse Smoke is specifically useful against setups which rely on defenders with precharged Specials. Finally, Zeke's base Def/Res Menace is still pretty good as far as general gameplay is concerned and makes him generally more self-sufficient in the stats control department. 

Weapon: Holy Gradivus

Assist: Positional Assist

Special: Moonbow / Bonfire / Ruptured Sky

Passive A: Atk/Def Catch 4 / Death Blow / Atk/Def Solo

Passive B: A/D Near Trace / Lull Atk/Def

Passive C: Atk/Def Menace / Def/Res Menace / Atk Smoke

Sacred Seal: Atk/Def Solo / Death Blow / Sturdy Blow

• Thanks to the guaranteed follow-up effect of Holy Gradivus, Zeke can run a pretty formidable (albeit comparable to Duessel) blitz-style build focused on building up damage and bringing down the enemy mainly by initiating combat. 
• Even though this build very closely resembles the first build (and plays mostly the same in most circumstances), a few changes can cater Zeke to a totally offensive approach. Of particular note are the optional additions of A/D Near Trace, a 2 CD Special, and Death Blow:
  • A/D Near Trace's in-combat debuffs are similar to Lull Atk/Def. However, Zeke trades the ability to nullify enemy buffs for post-combat movement, which can prove useful in escaping enemy range after a fight. Given that Zeke already comes with Lull by default and Trace skills are a little difficult to come by at this moment of writing, though, Lull Atk/Def is a perfectly good default.
  • Moonbow or Ruptured Sky as Zeke's Special are preferred over most things else as they are likely to activate in one round with their lower cooldown. If you're willing to put up with a slight delay for higher reward, Bonfire is still a great choice with Zeke's fantastic Defense stat. 
  • Though the likes of Atk/Def Catch and Solo have easy enough activation conditions that forgoing their dual-phase nature isn't entirely recommended, you can run Death Blow in the A-slot, Sacred Seal, or both for an easy Attack swing in player phase exclusively.