Shuriken is a weapon and a talisman.
The image of the ninja as using shurikens is influenced by Kabuki and period dramas. Of course, there were times when they used shuriken, but in fact, the modern view is that their main use was as amulets.
A few hundred years ago, iron was expensive and required a lot of skill to process. The reality is that the ninja were not rich enough to disperse them, that they were not enough weapons to inflict fatal wounds on their opponents, and that they were too heavy and noisy to carry many of them around, so they kept one or two in their pockets for protection.
I’ll add a note for people those who are shocked if I change ninja’s image too much. The stick shuriken (see photo below) was convenient to carry, economical, and could inflict damage on the opponent,so they took the prongs of long nail and used them a lot! It seems that they carried them by hiding them in leggings, handcuffs, or braided hats. Practical things are always simple, aren’t they?
And there is a view that the most well-known cross shuriken may have actually had the same meaning as the cross. The cross was brought to Japan by people from the west, and the ninja may have kept their minds strong by carrying the crossed shuriken, which has two crossed lines representing heaven and earth (light and shadow), as a talisman.
What do you carry to keep your mind strong?