The phrase "peculiar manner" means a unique or distinct way of doing something that is different from what is considered normal or ordinary. Full definition
The idea of detached bodies floating in space, of different sizes and densities, perhaps of different colors and temperatures, and surrounded and interlarded with wisps of gaseous condition, and some at rest, while others move in peculiar manners, seems to me the ideal source of form. (calder.org)
The name is pronounced in an extremely peculiar manner as well, «Sha - hn». (babygaga.com)