|A lot of the Inigo builds so far have showcased budget builds and builds that directly counter Lyn: Brave Lady and Reinhardt: Thunder's Fist, but lost in all of the discovery is that Inigo's offenses can be salvagable. As such, this build aims to take a more offensive approach.
+Spd offers more survivability and offensive presence, so this is the generally recommended boon. The most optimal bane is -Def, as with -Res he won't be able to survive certain key threats. This build mainly offers to take advantage of the high speed and access to Gronnblade+.
Gronnblade+ is the star of this set, and it's chosen to bolster his relatively mediocre offense to plausible use. Moonbow is chosen as his special, as it lets him combat higher-res mages more effectively. He likely won't see as much combat as other blade nukes you might field alongside him, so the shorter cooldown is generally recommended. Dance is his assist, and is really the only reason you'd consider using Inigo as a blade tome user.
Fury 3 gives him additional attack and speed, along with bulk, which may help him survive green nukes such as a Fury 3 Nino: Pious Mage buffed by Eirika: Restoration Lady and a fully-bladed Corrin: Novice Vacationer. And with Hones, he can stand to best Fury 3 Elise: Tropical Flower and Fury 3 Soren: Shrewd Strategist if they aren't +Spd nature or honed. Also to note, with this set, he can be able to KO Ike: Brave Mercenary if bladed up to 3/4/4/4.
Desperation 3 can let him KO these threats and others without the threat of getting KOed on a counter attack, while Wings of Mercy 3 bolsters his dancing utility by increasing his movement coverage.
Passive C is entirely flexible, but Hone Atk 3 is always an option, because he comes with it naturally.
Seals are flexible for the most part, but shoutouts go to Atk+3, Spd+3, and Quickened Pulse for boosting his offense, and HP+5 for helping him survive attacks from key threats such as most forms of Fury 3 Nino: Pious Mage and +Spd Fury 3 Elise: Tropical Flower.
Calculations are generally done, assuming he's boosted by a 3/4/2/4 set from Eirika: Restoration Lady or Ephraim: Restoration Lord. Teammate options include Eirika: Restoration Lady and Ephraim: Restoration Lord for boosting him, and both are excellent partners because of the triangle coverage they provide. Red and Blue bladetome mages also benefit from having Inigo as they they greatly appreciate his dancing utility, and overall provide great team synergy. This includes, but is not limited to Linde: Light Mage, Delthea: Free Spirit, Mae: Bundle of Energy, Tharja: Dark Shadow, Sanaki: Begnion's Apostle, Lilina: Delightful Noble, and Katarina: Wayward One. Cordelia: Perfect Bride, Innes: Regal Strategician, Leon: True of Heart, and Gaius: Thief Exposed also benefit greatly as teammates because they also get rid of problematic mages as well as appreciate the dancing utility, and overall have great synergy with a bladetome team + Eirika: Restoration Lady/Ephraim: Restoration Lord.
While Inigo's not the best blade tome user, he offers utility to separate himself from the rest. He exists as a backup nuke if you need it.