All 3 Uses of

whet
in
The Aeneid

Tyrrheus, the foster father of the beast, Then clench'd a hatchet in his horny fist, But held his hand from the descending stroke, And left his wedge within the cloven oak, To whet their courage and their rage provoke.†
Book 7 *

And, as a savage boar, on mountains bred, With forest mast and fatt'ning marshes fed, When once he sees himself in toils inclos'd, By huntsmen and their eager hounds oppos'd He whets his tusks, and turns, and dares the war; Th' invaders dart their jav'lins from afar: All keep aloof, and safely shout around; But none presumes to give a nearer wound: He frets and froths, erects his bristled hide, And shakes a grove of lances from his side: Not otherwise the troops, with hate inspir'd, And just revenge against the tyrant fir'd, Their darts with clamor at a distance drive, And only keep the languish'd war alive.†
Book 10

whets = increases a desire

Nor less the Trojan, in his Lemnian arms, To future fight his manly courage warms: He whets his fury, and with joy prepares To terminate at once the ling'ring wars; To cheer his chiefs and tender son, relates What Heav'n had promis'd, and expounds the fates.†
Book 12

Definition:

to increase a sense or desire

or: to sharpen a knife or other cutting edge