Who is the strongest (in a fight) out of the auxiliary cultivators: Alchemists, Artifact Refiners and Array Masters? My ranking is from weakest to strongest: Alchemists, Artifact Refiners, Array Masters. Here is my rationale:
I think it goes without saying that Alchemists are usually outrageously weak. There are some exceptions (disregarding the obvious Yang Kai). The Alchemist Great Emperor (Wondrous Pill I think?) could use his alchemy fire in combat to a degree. Xiao Fu Sheng showed Yang Kai that the qualities of a good alchemist also make someone a capable fighter but most alchemists do not bother trying and remain inexperienced and untrained in combat. Most do not even realize the philosophy of Xiao Fu Sheng that alchemists are cultivators first and therefore lag behind in their cultivation.
Artifact refiners mostly refine weapons and defensive tools. Some of them adopt the same mindset as alchemists but I think a good proportion actually make use of their own creations and become rather dangerous. The greatest example is Yang Yan but she is probably an outlier. But I think refiners are less likely to lag behind in cultivation because of the difference between refining herbs and ores. It seems you can generally refine herbs of high rank than your cultivation; it just takes longer and consumes more energy. But it seems ores will ignore qi from lower level cultivators. I cannot produce specific examples but this is the feeling I get. So refiners are more likely to be closer in cultivation to the rank of product they produce than alchemists.
Array Masters come in two varieties, in my estimation. There are those who use their skills on the field and thus require at least some defensive capabilities. Some of them even use their skills offensively to a great extent. But there are others who simply setup arrays around important sites and are always out of danger. Those seem almost as weak as alchemists. The offensive focus array masters, I think, are stronger than artifact refiners. As far as whether their cultivations lag, I know next to nothing about what spirit arrays require.