Condition Overload is highly recommended to take advantage of this weapon's high status chance and ability to proc Heat against enemies, greatly increasing its damage into the several hundreds if properly modded.
As with all broadswords, using the Heat Sword with Excalibur is advised in order to increase the weapon's damage and swing speed.
The last swing of Iron Phoenix's "Taking Flight" combo will trigger the weapon's slam attack and, thus, proc Heat against all enemies in range, allowing you to ignite enemies seamlessly without needing to jump and actually perform a slam if this stance is equipped. The mismatched polarities may discourage this, however, unless one is willing to expend a Forma.
Before Update 26.0 (2019-10-31), the Heat Sword used to emit a visible ring of fire from slam attacks. This visual effect was also shared with the Heat Dagger and Dual Heat Swords. Since then, all melee weapons make the same effect when doing slam attacks.
The Heat Sword received a visual change in Update 16.5 (2015-05-12), giving it a faded color scheme with texture animations similar to those found in Prisma weapons.
The Ember statue in the Strata Relay is holding a Heat Sword on its right hand.
Heat Sword in Codex.
Heat Sword - colour customisation
Warframe Heat Sword 2x Forma w Riven Mod Setup (U21.0.9)