Suggestions:
Customization - Players should be able to customize their characters with a large variety of clothing, hairstyles and accessories so that there are no players that are identical in every way.
Player HUD's - There should be a HUD above every players head showing their names and how much health they have just like in SAO to add a more graphical side to the game.
Classes - Players should be able to choose a class to go by in my personal opinion I think there should be Single Sword, Dual Sword, Spear, Axe and possibly a hammer class? each class would contain at least 30 skills for them to acquire and about 40+ weapons for them as well to add variety to their character's appearance and fighting style.
Fighting Styles - Players should be able to customize their fighting styles for example have their character have different option for holding weapons and attacking with them.
Weapons Upgrades - Players should be able to upgrade their weapons making them stronger and more durable, this gives players more things to aim for.
Weapon Crafting - There should be a weapon crafting system that allows players to gather the materials needed to create weapons to add an RPG feel to the game, having a large variety of weapons and materials will allow players to become sword collectors so that they have more activities.
Tailoring - Players should be able to create their own clothing by gathering things like "cloth", "silk", "metal" and more to create clothing and armor to give them a more active role when creating their characters.
Guild System - Players should be able to create guilds that actually play a role in the game for example; have guilds be able to control areas, have goals set by their leader, wars, houses and more. You could possibly make it so that guild leaders can add a customized logo for their guild which is printed onto their clothing or is shown above their heads.
Economy System - Players should be able to set up their own shops to sell their items that they have crafted/tailored. by doing this players have more of a role in the games economy instead of everything being run by Non-Playable characters.
Ranking System - Players should have their own ranks depending on their fighting abilities, level and stats for example; the person that is in one specific area for the longest time who is the strongest fighter there should be ranked as the ruler of that area obviously it will be subject to a vote so that it doesn't become unfair for people who are over-powered.
Player Titles - Players should be able to give themselves a title by adding a verb for players to submit a title change to an admin and if it is approved then that player will gain that title.
That concludes my suggestions for now, if you have any questions or if you want any more just contact me via my BYOND key.
Thank you, LegacyGaming.