This is an interesting thread (uh......except for the trip to fantasyland
but as Ariel notes, we've all got a little 'kid' left in us) and I've been looking into some things, which I hope will help with Vandoo's intent in examining these fascinating daggers. I know I've learned more on these, which I will share here, and would appreciate any clarification as required.
First of all, the dagger at the bottom of post #2 is indeed a khanjarli, which has the very recurved blade seem on khanjars, with the primary distinction apparantly the lunette shaped pommel, in this case ivory, but there are examples with buffalo horn or ebony known. Interestingly, the chiseled motif in the center of the blade amidst the fullering appears to be the 'kundalini flame' device often seen in the blades of many katars.
It is important to note that the recurved shape of these blades appears to actually be with reference to the shape of the buffalo horn, which was believed to have been used in earlier stabbing weapons. The reference to the scorpion or its sting appears to be more metaphorical, inferring the sting of death or to that effect. As mentioned by Vandoo, the scorpion has been used in such symbolism in many cultures over time.
As previously mentioned, the agrab (stylized scorpion image) is a well known device used on Arabian weapons to deflect the glance of the evil eye, with the scorpion presumably fearsome enough to have that effect.
As with many weapons and the often confounding terminology that is often associated with them, the term bichwa seems colloquially applied more than anything else. That doesnt help the double blade conundrum I guess
and this may have to do with Indian propensity for unusual and often multi-bladed weapons.
With these terms again, the term tiger tooth for daggers seems to be a case of intrerpolation of metaphoric terms. As with the bagh-nakh, the fearsome looking set of tiger claws, some daggers are referred to as the tigers claw I believe. It seems I have seen some unfounded reference to tiger tooth used regarding daggers, but that seems to have been unsubstantiated.
The term 'tooth' with reference to daggers may be associated with the term jamadhar, which as discussed years ago, is the proper term for the transverse grip daggers we all know as the katar. The error is traced back to Egerton, and was carried forward by subsequent writers.
Loosely interpreted, the 'jamadhar' term from Sanskrit terms means the 'tooth of death', without complex etymological breakdown.
The term 'tooth' of course also may be considered with the materials used in the hilts of these weapons, where walrus tooth was often a source of ivory,
and perhaps zoological elements might have inspired phraseology.
All best regards,