Viper's Tooth

The Viper's Tooth was a legendary khopesh laced with a highly virulent poison for which it earned its snake symbolism.

Description
With its golden blade and hilt, the Viper's Tooth was a powerful sword which did not hide its legendary status. Like any khopesh, its blade sharply arched forward before curving back to align back with the hilt, but this blade was superbly keen in comparison to other contemporary sickle swords. Aside from the evidently sharp back edge, the tip also tapered to a fine point.

The deadliest aspect of the Viper's Tooth, however, stemmed from its venom from which its name is derived. The poison laced onto the blade was so virulent that it frequently emitted toxic, purple fumes. Although the poison is likened to that of a viper's fang, in truth, the effects are dissimilar. Those struck by the blade would experience extreme nausea and disorienting pain before their organs rupture shortly after, killing them. The poison was also highly contagious, as the bodies of afflicted individuals would emit the toxic fumes that could poison anyone exposed to it. In some situations, death is preceded by vomiting.

Reference

 * Assassin's Creed: Origins