with having a good time, getting ahead a little in the world, and protecting himself from harm. He isn't the type to let a promise inconvenience him or put himself in the way of an arrow on a battlefield. As he says, what is honor?

Can honor set to a
leg? No. Or an arm? No. Or take away the grief of a
wound? No. Honor hath no skill in surgery, then?
No. What is honor? A word. What is in that word
'honor'?

Falstaff's not a person you can depend on in a crisis—that is, you can only depend on him not to be around. He calls himself "a coward on instinct."

Hotspur, on the other hand, is too obsessed with honor. He's "too hard." It makes him a poor leader, because he is judgmental and holds everybody to too high a standard. He is no room for the values diplomats or courtiers might bring to a situation: all he can see is a glorious battle before him, and isn't one to stop and consider whether he is rushing into a situation rashly when he believes his all-important honor is at stake. He is overconfident, too, about his ability to achieve honor and this leads him to seek honor even when his troops are outnumbered. He says:

By heaven, methinks it were an easy leap
To pluck bright honor from the pale-faced moon

Hal, on the other hand, is "just right." You can depend on him to do the right thing, as you can't on Falstaff. At the same time, he is not ready to rush willy-nilly into a fight when it doesn't make good sense. He is able to get along with all sorts of people, not just military types, and is able to evaluate a situation from a variety of different angles. You might think at the beginning he is just a party animal, but he protects his father on the battlefield and isn't afraid to go one-on-one with Hotspur, essentially saying"it's you or me, buddy." This is illustrated here:

Two stars keep not their motion in one sphere,
Nor can one England brook a double reign
Of Harry Percy and the Prince of Wales.

In the wartime world of the play, honour is important.

Prince Hal is the first born son of Henry IV and therefore he knows that he will one day be king.  He knows his duty which includes a code of honour.  For the moment, he is content to sow his wild oats.  He speaks of all of this in Act I, scene 3 in a soliloquy at the end of the scene.  Does he want to be king?  "So when this loose behaviour I throw off/And pay the debt I never promised,..." It doesn't sounds like he does, at least at this point in his journey.

Hotspur as his name implies is hot tempered.  His honour will not permit him to give his prisoners to the king.  In fact, in Hotspur's world the king is not an honourable man.  If it had not been for Hotspur, his father the Earl of Northumberland and the Earl of Worcester, Henry would not be King Henry IV.  Their support in their opinion was honourable whereas Henry proved to be dishhonourable.

Falstaff is the realist about honour.  He speaks about it at the end of Act V, scene 1.  For him, honour is just a word that has no practical application.  It can't mend a broken arm or leg.  It can't perform surgery or take away pain or grief.  The dead have honour not the living.  It has no senses.  He concludes that, "Honour is a mere scutcheon" and tells us he wants nothing to do with it.

Each man holds a different view of honour with Hotspur and Falstaff representing the extremes.  For Prince Hal, it is part of his duty as the future king and when the time comes he behaves honourably.