Hindu or Muslim?
 

This piece had recently come in when I visited Artzi in Israel.

http://www.oriental-arms.co.il/item.php?id=5689

He identified it simply as a "khanjar", which I gather is a pretty generic term sometimes used synonymously with jambiya. The blade resembles those on daggers identified as a khanjarli, more than a typical jambiya blade, which fits the Indian association. However, I did not see anything that matched it well in Tirri's book.

Opinions on whether it is more likely Hindu or Muslim?

1. This is both Indian and Muslim - it is Moghul, who were Muslim Indians

2. Yes it is a khanjar which a generic term, especially in use there for this type of knife

3. Tirri's book is questionable at best.

What better sources do you recommend that are in print or at least affordable?

Start with the garden variety George Cameron Stone: great source and inexpensive on Amazon.
Egerton is useful and available. Elgood's book is excellent re. Hindu weapons, but khanjars are not well represented there: too Moghul :-)

Books
 

Thanks. I have all three on order (actually the Stone book arrives next time I turn on my iPad).