Analysis of knights

Where is the grave of Sir Arthur O'Kellyn?
Where may the grave of that good man be?--
By the side of a spring, on the breast of Helvellyn,
Under the twigs of a young birch tree!
The oak that in summer was sweet to hear,
And rustled its leaves in the fall of the year,
And whistled and roared in the winter alone,
Is gone,--and the birch in its stead is grown.--
The Knight's bones are dust,
And his good sword rust;--
His soul is with the saints, I trust.