Niles

Weapon: Spendthrift Bow+ (+RES/SPD) / Niles’s Bow (+Eff)

Assist: Positional Assist / Flexible

Special: Noontime / Sol 

Passive A: Mirror Stance / Kestrel Stance / Atk/Spd Solo / Atk/Res Solo 

Passive B: Null C-Disrupt / Null Follow-Up / Mystic Boost / Quick Riposte

Passive C: Pulse Smoke / Smoke Skills / Flexible

Sacred Seal: Atk/Spd Solo / Spd/Res Solo / Mystic Boost / Swift Stance / Mirror Stance / Quick Riposte

• Niles’s innate strengths—namely, his combination of decent Speed and Resistance—lend themselves well to an Enemy Phase anti-ranged set, even in an AR-O setting given the sufficient support and investment. He greatly appreciates receiving a +ATK IV to supplement his damage, but +RES and +SPD also works nicely to pad his survivability.
• The inheritable Spendthrift Bow makes for a stellar weapon choice to simultaneously enhance his damage and raw durability, with its detriment being well worth the benefits it brings—and if Brave Lucina’s refined Geirskögul is available, it can easily be offset as well. This is a rather significant investment, though, so his exclusive Niles’s Bow can also work for its built-in Special acceleration effects. 
• Relying on Niles’s stats alone generally won’t be enough to maintain high health (especially in Aether Raids), so equipping him with a healing Special is highly recommended. If using Spendthrift Bow, Noontime will always be preferred and pairs especially well with Brave Lucina support, though it may also be used with Niles’s Bow. Sol is another option when combining both Brave Lucina and his PRF’s built-in Slaying effect for immediate Special activations. 
• Mirror Stance and Kestrel Stance are excellent defensive A slot options to augment his key stats during the Enemy Phase and delay enemy Specials. If pure stat boosts are preferred, Atk/Spd Solo and Atk/Res Solo both work excellently and come with the benefit of having dual phase functionality. 
  • Niles generally needs all the stat boosts he can get, so Close Foil or Close Counter don’t work particularly well with him—especially due to his innately low physical bulk—but they may be worth considering if one feels confident enough in his tanking ability. 
• For his B slot, Null C-Disrupt and Null Follow-Up are both heavily meta-relevant skills that help him work around otherwise troublesome enemy mechanics, such as counterattack negation and built-in follow-ups respectively. Mystic Boost is another candidate that helps Niles’ more confidently combat Wrathful Staff healers and dragons while granting some appreciable healing, or Quick Riposte if nothing else to ensure his follow-up.
• For those willing to pull out all the stops for the Nohrian archer, Pulse Smoke is highly recommended for the purposes of Aether Raids Offense to shut down the ever-punishing and ubiquitous Infantry Pulse setups. Otherwise, simple stat-debuffing skills like Atk Smoke work perfectly well to enhance his Enemy Phase prowess. 
• Niles’s Sacred Seal slot can be filled by any available option that enhances his key stats (such as Atk/Spd Solo and Spd/Res Solo), or Quick Riposte if aiming to ensure his follow-up without relying purely on his Speed. Mystic Boost may also be considered for improved performance against certain magical threats and/or its attached healing.

Weapon: Niles’ Bow (+Eff)

Assist: Positional Assist / Flexible

Special: Glacies / Iceberg / Luna 

Passive A: Sturdy Impact / Atk/Spd Solo / Mirror Impact / Swift Sparrow / Fury

Passive B: Lull Atk/Spd / Null Follow-Up / Desperation / Special Spiral

Passive C: Smoke Skills / Joint Drive Skills / Wave Skills / Time’s Pulse / Flexible

Sacred Seal: Atk/Spd Solo / Atk/Def Solo / Death Blow / Swift Sparrow / Sturdy Blow

• He can also opt for a more aggressive approach and utilize a Player Phase oriented setup, centered around maximizing his damage and the use of his PRF. Accordingly, a boost to either one of his offensive stats with the appropriate Asset is ideal.
• His Special choice will be primarily dependent on his choice of B slot skill. Thanks to the properties of his PRF, Niles benefits from both a flat cooldown reduction (akin to Slaying weapons) and built-in Flashing Blade, thus making Glacies a rather strong and consistent choice for general usage. If using Desperation (or Special Spiral for Special activation chains), Iceberg and Luna are preferred. 
• Sturdy Impact is a phenomenal A slot skill to supplement Niles’s damage and survivability, doing a great deal to circumvent his otherwise poor physical durability; its Resistance-based alternative, Mirror Impact, should only be used in combination with Special Spiral and Iceberg for maximum damage sets. 
  • However, these do come with the downside of doing nothing to enhance his Speed—which he relies on for both doubles and his PRF—so more generally useful and available alternatives include Atk/Spd Solo, Swift Sparrow, and Fury. 
• Lull Atk/Spd works wonderfully to boost the archer’s survivability and consistency at doubling, especially through its ability to break through enemy bonuses. Niles’s B slot is rather diverse, though, and can also be filled by other offensive skills such as Null Follow-Up (to break through forms of follow-up denial), Desperation (for successive doubles), and Special Spiral (for Special chains).
• Niles has a flexible C slot that can be occupied by pretty much anything; however, there are some standouts. Smoke skills are always solid when provided with refresher support, Joint Drives work nicely for mutual buffing to himself and nearby allies, and Time’s Pulse assists his damage by allowing him to access his Special sooner. Any Sacred Seal that supplements his Attack or Speed will work here.