Mushir
Yes; Mushir (مشير) is Arabic in origin and denotes an adviser or counselor. It has also been used historically as an honorific.
No; Mushir as a proper name or title is not a Qur'anic proper noun. Its usage is lexical and historical rather than a Qur'anic given name.
Yes; the term was used in Arabic administrative and literary contexts. Its Ottoman cognate Müşir was used as a high military rank.
Yes; it is rare but culturally appropriate as a masculine Muslim name conveying counsel and leadership.
Mushir suggests trusted counsel, advisory capacity, and sometimes formal administrative or military rank in historical contexts.