Are they legendary stars?

[A. G. Maisey]

This effect of little white dots that appear to be just below the surface of the material is sometimes found in some lower quality Javanese keris.

According Prof. Jerzy Piaskowski the renowned Polish historical metallurgist, this effect is caused by cold forging.

Blade smiths will often pack a blade, especially the cutting edge, within the heat range that applies to cold forging.