I wanna preface this saying that I'm not trying to call you out or anything. However, if you are struggling with PP maintenance you cannot criticise ANYTHING that will help maintain PP. Whether it is food, SSAs, potentials etc. Radiant response intentionally gives low returns as it affects multiple aspects of PP. Active (not really relevant for partizan), Passive and PP cost reduction. If you are using atra it is a brilliant SSA for partizan and the only other real choice aside from the PP regen while guarding thing (I think it is heavenly protection). I could just as easily say 'struggling with PP? just get better xDDD' as there are players who play partizan with full damage SSAs (I used to but had to change it for endless and it stuck with me) and they can still manage the weapon fine due to expertise. Remember: Uptime will mostly trump raw power so if you have to fill all SSA slots with PP regen aids then that's how it goes. It isn't uncommon for people to do that with their partizan, especially if it isn't their main weapon. And as a matter of fact partizan mains even have a PP regen partizan (again I don't because I'm lazy but ideally I would) so they can still do damage while being able to manage their PP better.

Anyway the point is ANY SSA that helps PP in some way is useful. There is a new one called heavenly keeper or something that is pretty awesome considering it is -8% PP Consumption Reduction while in the air and +20% Natural & Attack PP Recovery while on the ground. I personally use cursed radiance because of the large PP you can get back. Considering it is per damage taken it also gives you godlike PP regen when statused with burn or poison and weak multihits immediately fill you up. If you use lethal intent S1 and cursed radiance (S2, S3 or both) then you get back 15%/30% of your PP every 20 seconds guaranteed.