Nursery Rhyme. Clxxxvi. Riddles

[A pen.]

When I was taken from the fair body,
They then cut off my head,
And thus my shape was altered;
It's I that make peace between king and king,
And many a true lover glad:
All this I do and ten times more,
And more I could do still,
But nothing can I do,
Without my guider's will.