1. This game is in dire need of a casual duel mode that lets any players (even same faction) fight each other purely for fun - no units in hospital or dead. You have a really cool combat system in this game, with a lot of PvP depth that is undiscovered due to the insanely high costs of engaging in PvP. One of the two players will likely lose everything, and be in the hospital for many days, if not weeks behind in resources, while the winner will still probably lose a large chunk of their army if the match is close in power. The current duel system plays a very important role in the game, however, don't get me wrong, duels are actually a super fun aspect of the game that a large majority of the players will simply never partake in due to the risk of being out of commission for multiple days.
2. I think that to take this game to the next level (just look at successful games like Clash Royale), you will need to implement a ranked PvP ladder system. This could be as simple as an ELO based ladder where you queue up, fight other players (same rules as tactics school), and the winner increases in rating while the loser decreases. You could get cute with match making by having each player set up a ranked deployment and then create ladder brackets based on deployment power rather than total power, but i'd honestly take any sort of ranked PvP over nothing. I would also suggest that playing this costs no energy, as letting people play it a ton would likely pay off in linari purchases anyway.
As an avid PvP gamer, I hope that you will consider pushing PvP further in AoC. You have something special here when it comes to pvp combat that suites a mobile plat fom incredibly well, which is not easy to find.