Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
Rust in a dream is corruption in religion and committing sins. Rust on a sword indicates an unrighteous son. Rust on a mirror indicates the bad state of the wife.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
Rust indicates people of heresy and misguidance. Whoever sees himself removing rust is repenting from a sin.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
Rust is interpreted as a hypocritical man. Whoever sees that one of his belongings is rusty is befriending a bad man.