Glauce is one exceptional nurse. Her devotion to Britomart in Book 3, where she even disguises herself as a man along side her mistress, makes her a lot more relatable than the wise but distant Palmer.
When Glauce first tries to heal Britomart's love-sickness for Arthegall, she turns to magic and potions. Although these don't work, we can see her as a kind of minor foil to the evil Busirane, who also turns to magic to solve problems of love, but does so with deeply malicious intentions.
Glauce's relationship to Britomart is also one of the only female-female friendships we seen in the poem and gives us a window onto Britomart's more conventional life as a woman before she takes up the arms of a man. Glauce's willingness to join Britomart in her cross-dressing disguise and her travels as a knight extends Glauce's feminine association with Britomart to Britomart's overall status as a great knight. Glauce might be the only character that connects Britomart to both her life as a refined lady and her life as a fearsome knight.