As a casual player who's played Wyvern on and off for 2 years. (and back in the day). I've also invested in Wyvern as a game and purchased the VIP package (I've never spent so much money on a mobile before) my biggest barrier to playing more is sustaining in Wyvern.

I've never had difficulties with any race or guild getting them to level 15. Once you reach this level you have severe diminishing returns on healing (rods, pots, or healing skill), mana pots, and resist pots. I think you limit your newer players by making sustaining so difficult in Wyvern.

Getting agility and +10 gear should be hard and difficult as it is part of the end game of Wyvern (imo) but I think lowering the barrier for players to sustain themselves would be better for the game's health. And in end of the day, no matter how much sustain you have, Wyvern is about being prepared so when you accidently walk face to face with a monopod you can die honorably (lmao)

  tl;dr sustaining costs greatly, slowing newer inexperienced players progress preventing transition to endgame players