There are two unused items in the game's code. The first being a brownish orb which is named "?". Its animation is that of a curing item, but has no visible effects.

The second item is called "Ruby Armet". It is only equippable by Purim (the girl), and offers 46 magic defense and defense. The official Secret of Mana Guidebook still lists it as an available item, even giving it a price and concept art. It also includes this description:

重みを肩で支えることができる構造になっているため,力がなくても動きやすい中量級へルム。また中央にあしらわれた真紅のルビーは,炎のダメ一ジを軽減する効果をもっている。

Which translated says:

This is a midclass helm that does not take energy to move in easily because the structure is such that the weight is supported by the shoulders. Also, with the deep red ruby in its center, it reduces the effectiveness of flame damage attacks.