Critical bugfixes - Part 2

Some more post-submission critical bugfixes:

• Lowered music volume.
• The player's weapon is intended to be based on their chosen stats, but a typo was preventing this and has been fixed.
• Some items were not contributing their values to the correct stats. They now do.
• Dealing more damage to enemies than their remaining health would result in a negative value, and thus the enemy would become unkillable. Enemies now correctly die when at negative health.