I started to play this game a while ago and during tha short time some ideas came to my mind.. here they are
Armor/Weapon Mastery - my idea is that u can spend 1 skill point into dedicated weapon mastery and 1 for armor mastery, it would give 5% dmg or def. So players can choose if spend all their skill points for active skills or sacrifice 1 or 2 for passive. Let's say u can only choose 1 path of weapon or armor mastery (cause casters have only 1 path of weapon and armor mastery)
New weapons/armors - it would be nice to have more weapon and armor diversity, I would appriciate more stuff with drain and atack speed, maybe some slight skill cooldown items for fighters??
Sixth skill - as the world of WS is progressing it would also be nice to have some new skills, I was thinking about a list of 5 or 10 skills from witch u can choose only 1 skill at 15 lvl and the choise will be permanent. It doesnt have to be staight atack skills. I was more thinking about skills like Resurection, increasement of stats for short period of time, party heal or something.. but with huge cooldown!
Mail service - briliant thing from Lineage 2. As I found it very difficult to transfer items and gold from one side to another it would be lovely to have mail service. Mail could contain 5 items and u can sent it to any player. All u will have to do is put player's name into column add items or gold and press "send". Recieving will be similar like when u recieve a gift from Miracle shop. "Open" then check whats in and press "to bag"
More customization and Wings - Well these are just my wishies :D I would love to add lighting or burning visual efect on weapons or something and because I used to play MU online a lot It would be awesome to have a quest or something at lvl 20 to make a wings (angel or demon - depends on the side). It would take place in costume slot and character will be flying insted of walking.