"My dearest Divya,
...Finally I have managed to get the required information. The sign is basically an arms inspector's mark. The arrow (referred to in the army as a Broad Arrow) signifies the fact that the weapon belongs to the army. T stands for Technical, E for Establishment and (W) for Weapon. D is the inspectors personal mark. I hope this makes sense."
Well, it makes sense to me---much more so than the WAGs I have seen on the internet before this.
Reference books all list this mark as "unknown"---including "India's Enfields" who's author had good connections inside the Indian Army, himself.
So this is offered without guarantees.
-----krinko