A heady metaphor for the taste of vengeance, followed by the bitter aftertaste. It reminds me of a quotation by Nelson Mandela along the lines that resentment poisons you before it kills your enemy.

‘Something of vengeance I had tasted for the first time; as aromatic wine it seemed, on swallowing, warm and racy: its after-flavour, metallic and corroding, gave me a sensation as if I had been poisoned.’

Source: Charlotte Bronte,Jane Eyre (London: Bounty Books, 2012 (1847)), p. 43