SR20 Student Pilot reported during engine malfunction at night; CFI froze leaving student to fly and handle situation to a landing. Student reported being in an unsafe situation by CFII who failed to assist and handle situation.

Narrative

While practicing the RNAV-D to ZZZ; began climb to 7;400 from 6;000 en route to ZZZ1; engine began to make loud rhythmic knocking sound. Engine was banging and knocking and would worsen with added power. Airplane could no longer climb or maintain altitude. I indicated the issue to my instructor and prompted her to contact ATC. My instructor called ATC stating 'our engine is making a vibration and noise' ATC responding asking for clarity on the nature of her call and if we were Requesting Priority. My instructor did not respond to ATC; after a few moments; I took over. I called to ATC and told them we are requesting priority and need vectored to the nearest airport. ATC continued to give directions and gave us priority to land at ZZZ. During the entirety of this event; I was the sole manipulator of the controls and my instructor did not help during priority. My CFI froze in priority situation while I was flying under goggles at night; I cannot think of a scenario where it is acceptable to have a trainee handle priority of that type as a CFII. After landing; we taxied to the FBO. My instructor spoke to flight safety personnel on the ground and assured me that a report was made and that I would not need to write a statement. I later found that that information was inaccurate. I was put in an unsafe position where I had to be PIC in priority as a trainee. My instructor was not a participant in landing after the priority was requested. I am glad that my prior training was enough to get me through this priority; but if I had not reacted quickly and taken controls; the situation could have ended catastrophically. I suggest the CFII be grounded and given a review prior to flight with other students. Instructor needs to be proficient in priority procedures and reevaluated.