In The Elder Scrolls IV: Oblivion (including Oblivion Remastered), Glow Dust can be obtained in several ways:

• From Will-o-the-Wisps : These are floating, glowing enemies found mainly in forests, swamps, and certain caves in Cyrodiil, especially at night or in foggy areas. Notable locations include Blackwood area and caves like Crayfish Cave, Breakneck Cave, Wind Cave, Bramblepoint Cave, and Arrowshaft Cavern. Will-o-the-Wisps are resistant to normal weapons and require enchanted weapons or magic spells to be defeated and drop Glow Dust

• Buying from Merchants : Glow Dust can be purchased from alchemy shops in the Imperial City Market District. Key vendors include Ogier Georick at The Main Ingredient and Claudette Perrick at The Gilded Carafe. These shops restock Glow Dust approximately every 48 to 73 hours, allowing you to buy more over time. You may also find Glow Dust at Calindil’s Mystic Emporium if your Mercantile skill is high enough

• Quest-related Will-o-the-Wisps : Some specific Will-o-the-Wisps appear only during certain quests, such as near Azura's Shrine after starting the "Blood of the Daedra" quest, or outside Swampy Cave after beginning the Fighters Guild quest "Mystery at Harlun's Watch"

In summary, the easiest ways to get Glow Dust are either killing Will-o-the- Wisps with magic or enchanted weapons or buying it from alchemy shops in the Imperial City Market District