Many religions, and religious orders teach control and mastery of mind and body. This is particularly the case where followers of a religion are oppressed and cannot openly carry weapons of self-defense. The claim that there's no lore-based reason for a sneaky priestess simply eludes me. What is sneakiness? It's nothing more than applied awareness of and control over the body. The original purpose may not have been to sneak, but the effect is exactly the same. Religious orders teach meditation, teach patience, teach control of the body and stillness of the mind, the body and the soul. Yogis are taught to be indifferent to pain or cold, and control over the circulatory system so that they do not bleed, for example. Some teach their followers to have as little impact on the world as possible, and to be a friend rather than an antagonist to it. Think of St. Francis of Assisi, for example. Walk softly, carefully, quietly, aware of your own movement, conscious of where you step. Don't startle the birds and animals. This may not be taught as sneakiness as such, but again the effect is the same, just applied to a different purpose. "It is said, a Shao-Lin monk can walk through walls. Looked for, he cannot be seen. Listened for, he cannot be heard" "This rice-paper is the test, fragile as the wings of a butterfly! When you can walk its length and leave no trace, you will have learned."