Great work.
1. The clicking the sword cursor needs to be disabled for a second or even two when the options open as most of the time my next sword click was choosing a powerup before I had even read what they were. Could it just be a spinning blade on the mouse cursor, then clicking could be used for other things (see points below).
2. Some obstacles on the map and maybe some droppable obstacles would take this up a notch especially to the TD crowd.
3. The defences could also be positionable towers.
4. The feel of the sword strike seemed off, maybe it's me or the trail but a few times I was convinced I had hit the enemy but appeared not to.
5. Or you could take it more RTS with swordsmen and archers that the player can select and command on the map.