Rust boosts Normal attack damage by 40% (up to 80% when fully refined). But this buff is accompanied by a little debuff, where Rust will decrease the damage of charged attacks. This 40% damage buff applies to Childe when he's attacking in his melee stance, so it's highly viable for him.

Does rust affect Childe Genshin?

In conclusion, Using The Rust, the dmg dealt from Childe meele stance increased by 35%, roughly near The Rust effect, which is 40%. Assuming that some DMG is dampened by unknown factor, it's safe to assume that The Rust effect applies to Childe meele stance.

Does rust work on Tartaglia?

Best Weapons for Tartaglia in Genshin Impact

But this time it has to be the Rust bow for a solid 4-star weapon. Tartaglia thrives on inflicting Riptide on his opponents, which can be done be shooting a charged shot - but the Rust bow actually weakens aimed shots.