Instead of adding new orbs. Make the orbs combine! (This is prob a really big thing to actually implement)
But it would be so cool to be able to combine the orbs. Say equipping a blue and a green orb would make the sword from the green orb to travel forward while attacking efficiently increasing its range.
My personal feeling when it came to orbs was that I just equipped the same orb twice since each setup I used was good at one specific thing. This meant that equipping two different orbs didnt really cut it for me. Now if each new orb unlocked alot of new abilites and quirks in the game THAT would be impressive and alot of fun to play around with.