Wa alaykum salam wa rahmatuLlahi wa barakatuHu,
In the Shafi’i School’s juristic nomenclature, the term “nass” is used to indicate that an opinion is one of Imam Shafi’s. And it is the relied-upon position of the Madhhab, while there is a weak “wajh” or “qawl mukharraj” that is also located in the School.
And the term “wajh” indicates to an opinion from the As-hab al-Wujuh. The term may be also featured in its dual or plural forms to indicate that there is a difference of opinion between the As-hab that consists of two or more opinions.
(See: al-Khaza’in al-Saniyyah 182)
And Allah knows best.
Answered by Shaykh Yaqub Abdurrahman