Thank you so much! I really appreciate the lengthly review. Right now I'm playing an actual old-school game "Yendorian Tales 3" and the UX is horrifying! So I'm glad I captured the feel of and old-school dungeon crawler without capturing the weaker parts.
The momentum system wasn't well explained. Basically if you hit the enemy and they miss you, you gain 1 momentum. If the enemy hits and you miss, you lose 1 momentum. If you both miss the momentum moves 1 point towards 0. The higher the number the bigger the attack bonuses you have. I couldn't figure out where to put this explanation so it didn't get communicated very clearly.
You are 100% correct about the exploit, spamming attack wasn't intentional. The Necromancer is very easy to kill this way! :) It's a really tough fight otherwise.
The Relic Sword and Relic Shield both glow as much as a torch so that helps. The game does a terrible job telling you this of course!
As for the caves there is a hidden object in each cave, Relic Sword and Relic Shield. The caves are massive though so it's easy to miss.