The game is supposed to be a permanent loop I'm afraid, the chest is only ever meant to be opened once - ever. The item inside is a random tribute to inspirations and testers, you don't need it to defeat the Balrog (don't wear his face - no really, I made the game do something ultra-mean if you do).
The red rogue wiki has all the lore: https://red-rogue.fandom.com/wiki/Red_Rogue_Wiki
If you activate Debug Mode (either backspace or shift+enter depending on version - check the wiki) you can look at the other items - but some are constructed specially. Fishbane's spear is probably the most fun, as is Mokesmoe's bug-weapon.