I have read that sectarian clashes in the past would sometimes become violent. Did some sects practice martial arts for defensive and/or offensive purposes?
Kumbh melas were apparently scenes of sectarian clashes at times:
nAgA sAdhus (ascetics) are a part of hindu sect who usually wander without clothes.
There are several sub sects of sampradayas among these. They are like warrior monks of Hinduism. They are usually seen in large numbers during kumbha melA, the largest hindu religious gathering.
They are well trained in wrestling and swordsmanship etc.
They can be vaishnava or shaiva etc.
The 13 Akharas are considered as the foundation of Hinduism and Naga Sadhus of these Akharas are considered as army of Akharas. Whenever in past Mughals, Mangols, British or other invaders tried to invade the country and attacked Hinduism; lakhs of Naga Sadhus martyred themselves to protect the religion.
To become a Naga of Vaishnav Akharas, Sadhus have to undergo long and rigorous training and rise step by step to higher echelons by proving their mettle to Nagateet who provides them warfare training. In a friendly talk, Shri Mahant of Nirmohi Ani, saint Madanmohan Das informed about the different posts of the Akhara to Free Press team at his camp located in Mangalnath zone. The junior most position of a Sadhu of the Akhara is known as Huddanga. After 3 years of rigorous training he rises to the position of Khiladi, followed by Rakmi and Nagapani. After a Nagapani attends all the Kumbh Mela’s of Allahabad, Nasik, Haridwar and Ujjain and also becomes skilled in warfare, he is promoted to the rank of Nagateet, which is the highest position in the cadre of Nagas. It takes 12 years for a Sadhu to become a Nagateet, said the saint. Initially Nagateets provide training of wrestling, swordsmanship and warfare to the newly inducted Huddanga’s in the Akhara. They are also promoted to the ranks of Mahnats and Shri Mahants in due course of time. A very few reach up to the rank of Jagadguru as per their potential.