Had a blast, very well done Zeldalike, a little too hard for average joe - enemies hit too hard, go down with one hits too many and attacks are too fast - but you know about that. I'm guessing the message about the game being too difficult shows after 10 deaths? I won't believe it's random :P
Liked the structure - optional bosses, semi-open world, picking up loot and money that can be repurposed. Enjoyed the puzzles too. I wasn't sure if that small hint from the stone guardian meant anything but it did! Crafting new weapons gives extra layer of fun. I'm not really a big fan of crafting games and yet here it actually gives additional purpose for slaying monsters and experimenting with new ingredients was always rewarding. I managed to create 14 swords out of 16, I managed to put the familiar sword without hints, I did chaos sword and wand sword with secrets from the books (reading the page for chaos recipe stopped the background animation). I kept trying to fit the pearl on the hilt but couldn't get anyting... Additional effects on swords are awesome, thorn, ghost, bone, wolf, chaos, it's not boring +1 to attack but with special powers, I loved that. Overall system for forging is simple and enjoyable, new weapons are a blast to find and use.
Those bosses though, I'd say they're overpowered but I used overpowered stone slab for two of them. The game definitely demands a player to learn some patterns. I'd say the initial area should be bigger, with weaker enemies, your sword should have a little bigger reach, enemies should have extra couple frames before attacking and we should have more invulnerability time (one mistake and half of your life is gone).
It's a great demo though, no gamebreaking bugs, no glitches, complete experience. I'm just afraid that keeping with NES zelda aesthethic might limit potential interest and moving it up to 16-bit counterpart would make it more appealing.
Still, awesome job so far!