My favorite deity in Chinese myth - Erlang Shen (二郎神).
Erlang is very often hailed nowadays as a god of war. But I’m not sure I agree with that role. The more traditional war gods in Chinese myth are actually Xing Tian (邢天) and Chi You (蚩尤), and I’d even argue that deities like Nezha (哪吒) is a more proper diety of war/battles than he is. Erlang is probably more accurately a martial god/sage (武圣). He’s less about the leading armies part of war and more about the kicking of butts. =P Hence, why he was called in to fight the Monkey King in “Journey to the West” when nobody else in the Heavens could match the monkey. But he was not often shown as a front line army/squad leader during the Shang-Zhou war in “Canonization of the Gods”.
More traditionally, he’s the patron deity of the Shu (蜀) region of China, which more or less encompasses the modern Sichuan region. (Kinda like how Athena was patron deity of Athens and so forth.) He’s also a god of the waterways (possibly civil engineering?), credited with helping the historical figure of Li Bing (李冰) build the Dujiangyan (都江堰) Irrigation System.
On a less serious vein, I also think he should be a deity of domestication (or Pokemon trainers XD). IIRC he’s the only major mythical figure who is associated with a varied retinue of pets. The most famous is the celestial hound Xiaotianquan (啸天犬), and he’s also known to have a hunting hawk and a silver horse. Fun fact - in “Canonization of the Gods”, all the other gods have a tendency to have one or a few major arcane artifacts which they would often use in during battle as their ‘ultimate attack’, in an RPG sense. Erlang, on the otherhand, never bothered with any artifacts. Instead, in the middle of battle, he would fling his dog out of his sleeve to maul his opponents face - to great effect. Now remember, in ancient China, the only pure breed of dogs is the ancestor of the modern Pekingese (and not the large bloodhound/german shepherd type dog that is depicted in more modern art). I have to admit, the mental image of a fluffy pekingese assassin puppy getting tossed out of a god’s sleeve made for a very hilarious mental image.