Wight is an enemy from Final Fantasy X-2.
Having elemental resistant abilities and equipment helps deal with their elemental spells, while having Deathproof completely nullifies their Doom spell. If none of these are available, using the Sacred Beast Garment Grid combined with strong physical attackers will maker quick work of them, or using Blessed Gems.
Wight refers to "a person of a specified kind, especially one regarded as unfortunate." In literary terms, it refers to "a spirit, ghost, or other supernatural being."