viperish tongue

His green, viperish tongue flicked over mottled lips.

Not that she intended to let Nynaeve know, her and her 'viperish tongue.

In backward centuries when slandering people often involved meeting one's victims in the flesh, there were restraints on the viperish tongue.

It did not take long to compare notes, though Elayne continued to show a viperish tongue; Nynaeve had had a perfectly good reason for screaming at Egwene, and Elayne probably had been dreaming of parading in front of Rand in her sequined costume, if not less.