This is one I had quite a lot of goes at because it's just good fun. Nice art style, simple but effective gameplay and definitely a feeling of being a brave knight fighting marauding monsters.
As a suggestion, I'd have half a second, maybe a second of temporary invincibility after taking damage. It's easy to lose 2 or 3 health in one go.
On the other hand it does present a good challenge, it's definitely not a pushover. Great entry!