Aman was resilient even at the face of danger. It was an admirable quality as a king , however he just put it to bad use. To be honest Aman was a great king , if one could look at necromancy as just another form of art , and ignore the fact that he usurped the throne , the guy was good ruler.
Aman was undoubtedly strong and charismatic, he was also courageous to lead by example and had a spine to fight stronger opponents head on. Only if his natural disposition was not leaning towards evil , he would have made a terrifying monarch.
Rudra personally had nothing against Aman , but the man was bad for buisness , many regions had severed trade ties with Hazelgroove once he took over the throne. There were mass riots and the church of light felt uncomfortable under a rumored necromancer as the ruler , hence abstaining from public support of the monarchy.