I've checked the GameFAQs walkthrough and the Half Minute Hero wiki article on this quest. I've bought the shield in the middle of the map. I've cleared out all the caves. I've checked all towns. Yet, the game tells me I have equpiment incomplete for this quest. What am I missing?
One thing that comes to mind might be that I could get a different end-of-quest award if I somehow avoided getting the Bomber title and destroyed the rock protecting this boss the hard way. However, 25 seconds of smashing at it at maximum level while dashing wasn't enough to crack it. Perhaps I need special equipment to get this done?
Not pictured: a way to take down that rock by hand, despite doing everything I can to maximize my attack statistic. Maximizing weight in effort to increase the amount of 2-damage hits per second was similarly unsuccessful.