Question Summary
What is the ruling of washing the nose in wudu?
Answer
In the Name of Allah, the Most Merciful and Compassionate
Washing the nostrils in wudu is an emphasized sunna. [Shurunbulali, Maraqi al -Falah]
For this reason, omitting washing the nostrils in wudu does not affect the validity of the wudu.
Note that you do not have to breathe in the water. [Tahtawi,Shurunbulali; Hashiyat Maraqi al-Falah]
You can merely cup some water in your hand and dip your nose therein. If even doing this causes you undue hardship, you may leave it.
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani