Not sure if the demo was supposed to end after gaining the second sword; but if so, I personally feel like for a demo it should include other stuff, like the world map, a town hub with clickable buildings... in fact, making areas you're in explorable by clicking them and initiating battles by clicking certain things would seem to make the most sense for a game like this (for reference, look at AdventureQuest's BattleOn town, basically that sort of observer view of each area).
As for smartphone vs PC, honestly as someone who has played both I'd say each has their own benefits. Touch would be easier to swipe (the mouse swipes are too weak), but clicking can be MUCH faster than touching in any scenario, so the longer shield times on PC are balanced by PC's faster attacks.
I agree with others about weak points, but at the same time I feel like slashes should deal more damage than stabs. Make it a multiplier based on where you attack... so basically the % damage increase from slashing a non-critical point should be less than the % damage increase from slashing a critical point compared to stabbing it.
Another quick suggestion - when the player character changes gear, any gear at all, please have a different character models that recognizes that change. It's a lot of models to draw but for a game like this there'll definitely be a finite amount (it's not an mmo, after all).
It would also be nice to have tons of options for player convenience, like an option to auto-equip better gear or not.
Lastly, mob tactics. One unique thing you could do is change the speed and size of enemy attack nodes depending on the enemy in question; the faster their attacks and/or the smaller the size of the nodes, the less damage each attack does. You can have enemies that mix and match this - so if a player goes up against a boss (like a dragon) that unleashes a ton of huge yet slow nodes at once, the player will suffer major damage from each attack; but even though the nodes are far larger and slower, on a boss like that there'd be a ton of nodes going off at once. You could even color-code nodes to where you can't remove one color without removing another (faint attacks) or colored nodes that have to be pressed within a close time of each other or else you fail to remove that group (dual attacks, arrow storm).
I love the setup of this game, and so long as there's an environment that prompts combat rather than just an endless line of enemies without rhyme or reason, I can see this being very, very successful in its full release.