The fast sword

Yes, because part of the grass sword wormed it's way in to the Finn sword. The green glow at the end of the episode tells you that something is going to happen with both the Grass Sword and the Finn Sword. So it did combined together but I don't know what's going to happen. If there is a future episode about the Finn Sword, we will find our what's really going to happen!

Look, i already know that junk

No offence doe