Bio Blade

Bio Blade, also known as Bio Sword or simply Bio, is a recurring ability in the series. It is generally a powerful Poison-elemental or Non-elemental Spellblade that can allow the user to inflict the Sap or Poison status when attacking physically. It usually requires having learned the spell Bio in order to use it.

Final Fantasy V
Bio is a level 4 Spellblade ability, costing 6 MP to cast. If a non-heavy enemy is weak to the Poison-element, it will instantly kill that enemy. Otherwise, against non-heavy enemies, the power of the user is quadrupled and their attack pierces the enemy's defense.

Final Fantasy IX
Bio Sword is a Sword Magic ability usable by Steiner while Vivi is in the party. It costs 20 MP to use and increases Steiner's attack by 20.