The Battle Menu is a menu where you can use battle-only items while in combat. To do this, while in combat, press the Triangle button, and a menu with two (or three) commands will appear. This is your Battle Menu, and it is your freedom train for during combat.
Some items that appear gray and unusable in your Main Menu can be used in combat. These include all books, jewelry, and other miscellaneous items. Herbs, Mugworts, and Mel's Elixirs cannot be used in battle.
When you select this option, you have a chance to escape a battle in the wild; at chances, you may even escape from boss battles. The only exception is the Levant battle, and all Arena battles (including the Genus Arenas).
This option is only available when you receive your wings. At the cost of a shield, you will revive a monster at 1 HP. If your BeastAmulet is not down by at least one when selecting this option, nothing will happen. After you lose your wings, this option will become obsolete, leaving you to use some items.