S. R. Faruqi:

kyaa jaano = what would you, or someone, know?

To say kyaa jaano instead of kyaa jaaniye is very fine, because in it there's a very direct address-- 'what would you people know?'. Then, in 'what do I know?' there's a negative rhetorical question (that is, 'I don't know', 'how should I know?'), and a sarcastic tone as well (that is, 'do you think that I know?').

The image in the second line, and the affinity of the glittering drop of blood with the red-whiteness of dawn, is fine. Muzaffar Ali Sayyid has given high praise to this verse from the first divan [{6,4}]:

jigar hii me;N ik qa:trah ;xuu;N hai sirishk
palak tak gayaa to talaa:tum kiyaa

[only/emphatically in the liver is it a single/particular/unique/excellent drop of blood, the tear--
when it went as far as the eyelashes then it created a wave-buffeting]

Undoubtedly the verse's pithiness is very fine, and for the drop of blood to reach the eyelashes and create a wave-buffeting is interesting. But in the present verse the faux-naïf attitude [tajaahul-e ((aarifaanah], and then the whole heart's becoming a single drop of blood-- and that too a glittering drop of blood-- are an absolutely new thought.

There's also the pleasure that the event took place at night, and in the verse there's no mention of the night-- and that night too, what a Doomsday-night it was!

FWP:

SETS == A,B; EK; INEXPRESSIBILITY
MOTIFS
NAMES
TERMS == FAUX-NAIF

The first line's sweeping professions of universal ignorance (Who knows anything? Not you! Not me!) are wonderfully ominous. Everybody is disclaiming not only responsibility for the fate of the heart, but even knowledge of it. It's something that's just not discussable. In this sense the verse is close to the very common 'inexpressibility trope' ('don't ask-- it's beyond words!'). Obviously such devices are ideally convenient and suitable in pithy little poems two lines long. But in fact they do create a more sinister effect than a long description could achieve, since they invite (and compel) us to use our own imagination.

Think of that scene in 'Jurassic Park' in which the first small quiver in a glass of water, and the tiniest little distant thump, are far more powerful than the eventual (and rather silly-looking) sight of the actual tyrannosaurus running after the jeep. The same ominous understatement helps make Henry James's 'The Turn of the Screw' so much more compelling than horror stories full of frenzied ghosts and monsters, lurching zombies, etc.

The idiomatic expression dil ko ;xuu;N karnaa , 'to turn the heart to blood', means to worry and vex oneself beyond endurance. The idiom works all the more elegantly here for being left implicit. Another, more explicit example in which Mir has used it:

{1058,7}.

There's also the cleverly pithy emphasis of ek , with its multivalent possibilities. Well might this be a special drop of blood, distilled as it is from the whole essence of the lover's heart! At least, so we assume. But it might instead be a bloody tear of regret for the loss of the heart, or of compassion for its unknown, and apparently unknowable, fate. This 'A,B' verse requires us to assemble the two lines into our own kind of coherence.