Dear Jim,
Your effort in bringing these sources together is appreciated; even whilst hampered by impaired access to your books. Since you refer to Pant I shall add the following from
A Catalogue of Arms & Armours in Bharat Kala Bhavan by Pant and Yashodhara Agrawal. As you see he uses the spelling Jaghnol, the same as Nicolle I believe? I have added his description of Tabar in order to clarify Tabar-Jaghnol.
Tabar – It was a single battle-axe consisting of a curved blade with a broad cutting edge. The wooden shaft was inserted into the socket of the blade. The sharp-edged blade was semi-circular. It had many sub-types. The size of the blade varied from 7 inches to 15 inches.
Jaghnol – It contained a steel handle and the head was thick and shaped like the beak of a bird. It had cutting edges on both the sides and a thickened point which was very useful in piercing a helmet or a coat of mail.
Tabar-Jaghnol – It was the combination of tabar and jaghnol hence the name. On one side it had the blade like that of the jaghnol and, opposite to it, one similar to that of a tabar.
There are no illustrations however. Note the reference to the steel handle and cutting edges.
The Weapons of War of the Indo Islamic Armies by A. I. Makki states the following:
Another favorite weapon was a narrow-bladed axe with a spike attached to its back that was used as an armor-piercing weapon (Jaghnol). Its use was widely popularized by the Ghurid armies and was later fashioned by the Rajputs into an advanced war weapon.
This can be found at:
http://www.alshindagah.com/marapr2006/islamic.html
Bally; your humility does you cerdit and Jim, yours too.
Best Regards.