It’s Lucina. The biggest surprise he’s found at Garreg Mach so far, and probably the largest mystery? He’s tested her, and so as she him.
It’s without saying that for some reason, she clearly has a wealth of combat experience, the kind that comes from being in large-scale fights for decades. Did Lucina serve as a general, like Zelgius? He’s still unsure as to if she is Branded, but it would explain all of her skill rather neatly.
Whatever it is, she has enough wealth in the way of the sword to match the Library of Alexandria, and Ike is determined to try and learn a thing or two. Meeting a match in swordplay has awakened the zealous irrepressible youth in him, and one that’s new and has so many things to teach makes him ecstatic.
There’s no doubt that Lucina is the pinnacle of singular swordsmanship? He’s not quite sure what to call it. In many ways, it’s similar to Marth, but the style itself is far heavier. Her blade dances, but it’s a swansong of fluttering steel and severing guillotine. There’s a an unpredictable grace to them, but it’s been honed with mechanical precision, like the Goddess’ Chosen... But alive and breathing. It fascinates him. It’s like Falchion has taken up a life of its own in her hands, telling him of a legacy and how each strike is meant to carve out a new path of her will.
Hence, in a straight fight, Ike actually has a disadvantage at start and may lose straight away-- because Lucina simply has more experience. Any sort of attack he makes is something she’s seen a variant of, and in turn, he has to learn from what she’s doing. Her defense is absolute, and proofed against the heavier bladestyle that Ike prefers, to a certain point. Ike has no illusions that Lucina, herself, holds the same strangely penetrating power that Marth has. Perhaps it’s just a trick of the eye, but he can swear her brand flashes like a newborn star as she executes them-- perhaps that’s the power she’s gained from her blood.
Most of the time, he’s quite happy to watch and spar like this, because every match he comes away has him feel the improvement. Look-- Ranulf, that’s a prodigy! Lucina is one! If anything, he’s just picking up notes...
Er, anyway, if he actually wanted to win, Lucina has a few notable... weaknesses? He wouldn’t really call them that, just things she hasn’t practiced much in. She’s supremely skilled at defense and adapting to changing battlefield conditions, so he suspects that she’s fought monsters usually larger than her, and something he’s started to suspect-- things with worse footwork than she has. It’s-- how does he describe this... Her footwork is perfect, but it’s a perfect defense. When she starts going on the offense, occasionally there’s a point where he feels like her adaptive footwork is meant to take advantage of things that are slower in adapting to her.
It tells that she’s not as used to fighting someone of her own strength in a pure duel, one-on-one. He’s also noticed that she actually seems to have a somewhat average pool of swordbreaking techniques. It might be that she doesn’t favor them, but Exalted Falchion’s design looks exactly like it was meant to catch swords and break them! She instead has focused on her pure striking power and speed, as well as associated technique. It’s true that she does use breaking techniques-- but it’s just a little strange that she didn’t build a style around the base of her weapon’s strength...
All that comes down to what Ike needs to approach Lucina with-- a balance of averages, with just a little extra added in. Lucina is great at defense and pivoting and striking at weakpoints, so he needs to maintain an average of all three as a defense. He can’t be lacking in anything, and most of all, he has to remain patient. What he needs to do next is leverage his two advantages-- greater reach, strength-- and he suspects, natural stamina. Lucina’s endurance is nearly unbreakable, but her pool of strength for offense will lose power if he keeps forcing her to parry or deflect his strikes. She could dodge, which is what she likely did against the monsters she fought, but if he maintains enough precision, she’ll be forced to meet his sword. For each exchange, he’ll put in the general strength he uses and add a bit more, likely in the middle of the parry, so she’s forced to have to expend her own to match it.
In other words, unlike a feral creature, he’ll prefer ‘chasing’ Lucina’s sword over striking at vital points or using his strength to overwhelm her in a burst. He will attempt to stall her and derive a pattern from her strikes or techniques, and other tells if he has the time. As the time slips by, he’ll adapt and increase the pressure on her, focusing on detecting and analyzing her pace and technique changes.
He’ll throw in Luna and Sol at times, just to replenish energy and push Lucina’s repository of stamina. He might use other blade techniques as well-- so long as he sees it drain the heavy fencer’s stamina, and doesn’t overcommit. Things like Wrath are right out for that reason, and he has a suspicion that Lucina has some resistance to esoteric skills, so he likely won’t use any of Ragnell’s flames. He won’t really use Aether-- he suspects Lucina will not give him the chance to. Unless she does the same, of course-- he’ll simply match that and clash with that in turn, then reset.
Things that aren’t swordplay? Oh, he’ll throw those in, too-- so long as their precision work and require focus to dispel. Kicks, likely, targeted at vital joints if he’s given the chance. He will leave his gauntlet hand free for combat options.
Ike has no illusions that Lucina won’t adapt at least several times. He recognizes that, and he is ready and willing to match.
...Right, he’s getting carried away. It’s been a long time since anyone’s pushed him to his limits! He has a right to be excited about this.
Maybe this is something he’d missed in his father’s swordsmanship. It turns out there was still more to go, after all. He’d suspected it. After all, Gawain had never lost in his prime. Perhaps this is why.
He’ll just have to work hard, and expand his horizons.
(asdlaksg im aware im incoherent, so unclear portion clarifications:
-Ike loses to Lucina on average at start. However, given time, he outramps her. --Ike’s tactical instinct and dueling adaptation are used to things that are stronger than him in most areas, where his only way of winning is to out-adapt all of those. Lucina fulfills those conditions.
-By putting pressure on her, he’s trying to chase her with Nihil to restrict her skill options. He does not expect this to last long.
-Skill use by him is optional, and he’s relying mostly on his greater stamina and laser focus to try and tide him through Lucina’s stamina. He has a suspicion that like Marth, she has an indomitable artificial pool, but lesser actual reserves-- so he’ll match her artificial pool with focus, and then chase through with his natural pool.
-‘Ike is a not a sword prodigy’ Poor self awareness. he’s a monster. Being able to match Zelgius of like 20 years of hardened swordsmanship in 6 years of combat is not natural in the slightest, especially since his inheritance is incomplete. Ranulf calls him out on it, and he has a nose for intrigue. He likely adapts within mere seconds of seeing a sword vector.)