Since I had to look this up (for a paper) I am sharing it all with you.
The passage in question:
Lo, as at English feasts, so I regreet
The daintiest last, to make the end most sweet:
O thou, the earthly author of my blood,
Whose youthful spirit, in me regenerate,
Doth with a twofold vigour lift me up
To reach at victory above my head,
Add proof unto mine armour with thy prayers;
And with thy blessings steel my lance's point,
That it may enter Mowbray's waxen coat,
And furbish new the name of John a Gaunt,
Even in the lusty havior of his son.
(Bolingbroke to Gaunt, RII 1.3)
R2, I.iii.68. About to fight, Bolingbroke embraces his father: 'The daintiest last, to make the end most sweet...author of my blood...with a two-fold vigour lift me up...steel my lance's point' that he 'may...furbish' their family name in his 'lusty haviour.' A metaphor for his becoming potent, virile, strong from this embrace, this physical contact with the author of his BLOOD (semen). His father with his dainties (DAINTY, testicle), his TWO-FOLD (testes) vigour, will lift him up, make the end sweet -- will STEEL (like an erect penis) the point (erection -- C;P) of his lance (weapon and penis -- P). However, Bolingbroke and his father both suffer a defeat: see CROOKED, where the same metaphor expresses deterioration.
The really sad part, though, is that I am both surprised and disappointed she does nothing with the "youthful spirit" line. IT IS RIGHT THERE AND IT IS OBVIOUS.