You know, I wrote this big long post, but it was mostly me whining about not liking how they’re implementing the Two-Handed keyword, and how despite the flavor text this card (based on the name and art) depicts a katana, not a no-dachi. And, really, who needs to read that?
As for playability? It could have some potential use, although it’s not something I’m planning on using. I’m not really sold on the notion of loading up one unit for all of your duels, but Dotanuki does have the potential to provide +2C from a single card with a 3FV (Naginata will grant the same Chi bonus for half the cost, but is only a 1FV). But that really seems like the extent of its usefulness, and even that’s pretty narrow. If you really want the +2C from one card that much, you can switch to Seppun’s Blessed Blade for one gold, always get the +2C (and maybe more Force) and be able to stack another Weapon on top of it – you’re really, really not going to be happy when your Dotanuki dueling unit can’t hit the guy that matters because your Personality + Weapon is only 4 or 5 Force.
And if you aren’t fixated on the +2C from one card, there are plenty of better options – you can get a +2F/+1C 3FV Weapon for 2G, and it isn’t Two-Handed. Or get a +3F/+1C non-Two-Handed Weapon for 4G with a variety of other upsides – a 4FV on Family Sword, honor meta on Justice of the Crane, card draw on Utaku’s Destiny, a 4FV and two abilities on Versatile Blade, and so forth.