So, I would pose this set of counterarguments to everyone freaking out over Russia's war in Ukraine and saying that China needs to supply Russia with arms so Russia can "win" in Ukraine:
A) It is of significant interest to China to ensure that Russia remains a stable nation that is able to maintain a trajectory where its future as a nation is not under existential threat, and China should be willing to make proportionate sacrifices and endure proportionate pain to ensure that Russia is not under existential threat of collapsing.
B) Regardless of how much Russia "wins" in a war in Ukraine, its economic consequences from the US/Europe/client states is already sealed and unlikely to be lifted.
C) The greatest existential threat to Russia is not how much Russia "wins" in Ukraine, but rather the economic and technological threats that it faces going forwards. How much Russia "wins" in Ukraine will not change those aforementioned economic and technological threats.
D) If China did provide Russia with military arms in the short term, it will only influence how much Russia "wins" in its war in Ukraine, but it will not change the economic and technological threats that Russia faces. However, China providing Russia with military arms will almost certainly result in greater economic and technological decoupling from the US/Europe/client states, in a manner that may be sooner and more destabilizing than China wishes.
E) Therefore, because Russia not being able to attain all of its political aims in Ukraine is not an existential threat to Russia, it does not make sense for China to provide military arms to Russia on the basis that China's interests for seeking Russia remains stable and not under threat of collapse. China providing military arms does not change Russia's own domestic stability.
F) Instead, the best thing China can do for Russia, is to provide Russia with economic and technological support in the short, medium and long term -- which China can best achieve, by further economically and technologically developing and advancing itself, which benefits from continued trade and somewhat stable relationships with the US/Europe/client states. China's trade and relationships with the US/Europe/client states therefore are only worth being degraded or sacrificed if there is a sufficient gain or risk that requires it to be done (for example, in event of a conflict over Taiwan).
China and West are already at war, and in the thick of it.
I believe you missed the whole point of what exactly is a modern war. War is not only for situations where bullets, bombs and body parts fly. Like you implied, war also includes and entails economic, technological, information and financial dimensions. In that sense, the war between US led western nations and China had already started and it's an open secret that somehow got hidden in plain sight. Just pick up any news sites and headlines screaming ongoing wars in stealth. So all your A to F gambles are kind of pointless procrastination bordering on pleading with an invincible power trying to avoid any and all pains as long as possible, landing you somewhere around denial and bargaining stages. The gloves are off really. I'm not sure why anybody still would want to stay in Western nations' good book. Russia is a litmus test for what level of prepared strategic mindset China leadership has, and so far I haven't found any disappointment yet.