~Relatively Heard-Of & Not Overly Difficult~
2-Handed Weapons - Not important by any means; Just opens up a little more dynamic options without much effort.
Day/ Night (Light/ Dark) System - Give your world somewhat of a natural feel?
Mail System - For those moments when your friends aren’t online & really want to tell them something before you forget what it is.
~Just a thought & some more advanced work to be done~
Have an option for Pets Called/ Summoned with Items that “level up by Exp.” to have some of the info be stored individually within’ that item as to retain it’s level & amount of Stat Points even if another Pet is Called/ Summoned so that when you Call/Summon the Item Pet again, it will be the same as when you "Release"d it. This would also allow for the trading of leveled-up Pets between Players.
Have an option for Pets Called/ Summoned with Spells, if they “level up by Exp.” would have some of their info stored within the Character info on that Account so every time that Character Calls/ Summons their Spell Pet that “levels up by Exp.”, they have the exact same Pet that they left off with before they switched out Pets.
-Again- Just a random thought I had while looking for Bugs.