Obscurity and William Shakespeare

Obscurity is an oft discussed topic in poetry, and a topic I will revisit again here soon. However,  as a teaser, I offer this. As I was reading Shakespeare's Henry VI, Part III, I came across this in Act II, Scene 6. It is spoken by Richard, the Duke of York's son (and soon to be villain in Richard III).

Revoke that doom of mercy, for 'tis Clifford,
Who not contented that he lopp'd the branch
In hewing Rutland, when his leaves put forth,
But set his murth'ring knife unto the root,
From whence...