Your making this in construct? And by multiplayer you mean online right?
It sound amazing imo.
1.looting.
The looting system sounds cool. This allows players to invest talent points in thievery if they like getting extra loot. Of course they would be sacrificing other talents but they would probably be the richest in all the land.
2. unique items.
I like the idea of a weapon or item sort of being extremely scarce. I haven't seen this before. In world of warcraft usually everyone gets a chance to get the sword of doom or something. I bet you would have bounty hunters trying to track down people lol.
3. Talent points
Having talent points instead of levels sounds pretty cool. But how would you get more talent points? Ssually a player levels up and gets increased stats or points of some sort to be used. You could give the player talent points if they kill a specific monster or do a task. In pokemon they have a system called EV training where you can grind on a specific enemy to gain its attributes. Of course in your game you could allow the player to do various duties to get stronger in a given area.