Jose, that point just means you're sharp!

You're right on the talismanic images, and there are so many applications. One I distinctly remember many years ago was the rabbits foot. It was really popular to wear one of these, until one pillar of wisdom noted, " if thats for good luck, I guess it didnt work too good for the rabbit!".
Still, one cannot diminish the power of positive thinking, belief and faith. In the many forms applied, these markings represent these profoundly, and often help us not only understand, but to identify the provenances of many weapons.
It seems that the triangular geometric applied device is primarily found in the folk religions of North Africa that are nominally Muslim, though it also occurs in Afghan and Central Asian regions, and is known as the 'fibula'. This is indeed to ward off the 'evil eye'. These triangular devices are found as described in a book titled "The Afghan Amulet" (I think by Sheila Payne) and appear worn on clothing and textiles. In North Africa the best example is the triangular linear motif on the flyssa blade.
I am not aware of the triangle used in this sense in Indian weapons, particularly the Hindu forms. In checking Elgood's "Hindu Arms and Ritual" I did not find specific reference to the 'evil eye' ...perhaps I missed it somewhere?
Gav, excellent! You found a copy of Wagner.....extremely important reference, and yes it is huge!! When I loaded my copy into our RV my wife really groaned as I brought it in

I had to convince her that I had left behind nearly a shelf of other books in its place.
Wagner is one of the few, actually probably the only, arms writer who has approached this very important esoterica in weapons, until Elgood that is!
Interesting observations Michael, the expression 'five in the eye' refers to the upheld hand with fingers splayed shielding from the evil eye, and as noted is termed 'fibula' (seems odd as one thinks of one of the two forearm bones).
Best regards,
Jim