Gameplay-wise, however, Odin's pretty meh as a mage and as a blue mage. He's competing with Linde, Olwen, Reinhardt, M!Robin, and whenever she's released, Ursula. Linde is a glass cannon, so he cannot compete with her damage, but he is still fairly fast and more bulkier and M!Robin is stronger, slightly slower, and just as durable as Odin, but more so to physical attacks. M!Robin also has Blarraven which is effective against grey units and does not increase his Special cooldown unlike Odin who has Blarblade. And then you have the recent mobile blue mages who have what are essentially Brave Tomes and Ursula, I don't remember what she does.
Part of it is stats. Odin's stats are balanced to the point where he doesn't do anything great and variations don't really help him nor hurt him that much. So, an Eliwood situation -- Blazing Sword that is since Heroes Eliwood is a resistance tank. Stat-wise, he's also the weakest as of now where on average, he's bested by Olwen by 1 point and is about 5 points off compared to M!Robin and Reinhardt. Balanced defenses are great, but they're not that off compared to Reinhardt, M!Robin, and even Olwen who basically trades 5 points of defense for 5 more to resistance. He only wins in HP and is the second-fastest blue mage as of now and not by much -- average of 3 points ahead of Olwen and M!Robin. HP doesn't really matter when his defenses aren't high or one of them isn't high allowing him to do something like tank physical attacks like Henry can.
The other part I want to say is more of his weapon rather than overall skills. Special is fine, Tomebreaker is great, and Defiant Attack helps. What doesn't help is a tome that adds to his Special cooldown and doesn't do anything great. It's not even a "Silver Tome" where it's straight-up damage and does not exist for mages for some reason. It adds damage from the buffs he gets, but why would you use him? Why use a mage with average all-around stats instead of Nino or Tharja who have much higher attack? Why not use a blue mage who can do something by default like Linde (pure damage), Olwen (Brave Tome), or Reinhardt (Brave Tome)? Why not use M!Robin who is also effective against grey units? That's 2 birds for 1 stone. They probably have a blue tome that's just damage. Had there been a "Silver Tome" for mages, Odin would have fared better with that. Considering that the developers probably don't want a random unit who's not that plot-relevant or has access to a legendary weapon for whatever reason, Odin with a unique tome isn't possible. That said, I think it would have been neat if Odin had access to a Killer Edge version of a tome as a reference to his Myrmidon roots. Alternatively, they could have made him into a physical and resistance tank who's fast, but does little damage. It would give him a niche at least.
I like Odin, I like his character, but as a unit, he's mediocre. It's weird since in Awakening, his magic growth was good and everyone knew that. Probably why he's a Dark Mage, a magic unit, in Fates and the only future kid to switch classes since he was better at something else. In Heroes, it's more like he might have been better if he was a physical unit who could have had access to something like Killer Edge for lower Special cooldown or even Missiletainn, his knock-off Mystletainn, which I don't know, could have done something weird like +3 to a random stat during combat. It's not really a big deal as Odin's a jack of all trades. He doesn't have any glaring flaws like Sophia being godawfully slow, Merric and Robin being really weak to magic for some reason, or Cecilia being very weak to physical attacks on top of being slow enough to be doubled. Of the ninth summon, he's by far one of the most stablest. It's just that of the 3 kids in Fates, he's really underwhelming. There could have been more to him is all I can say when you have hits like a truck and is fairly average all-around Laslow or fast and durable Selena who also acts as an anti-armor and anti-green unit.
