Nightfighter

Nightfighter (ナイトファイテ) is a rather common Ethereal, that appears in numerous worlds. But even though it is commonly found, and often fought, it is a high-ranking Ethereal, and is the most common Ethereal of that rank.

Like all Ethereal, it drops an material (in this case, the Energy Gem).

Fighting style
It attacks by slashing nearby targets with its Shuriken-like weapon, and often throws it at a distant target. It can also enchant its attacks with the power of any element, and therefore infliction more damage, and causing elemental effect. It has very low defense, but rather high magical defense, and all spellpower of its opponent is cut by half. If its MP gauge empties, it will use one the ability Osmose, which drains up to 15 MP of the target. When its HP reaches 10, it can activate its special ability, Nightshade, which poisons, and deals non-elemental magical damage to the chosen target. There is no way to remove that effect without getting rid of the Nightfighter first.

Trivia

 * The Nightfighters shuriken-like weapon is based off the lower part of the Ethereal symbol.