The Damascus steel was a sign of quality in the 19th century. After the advent of fluid steel barrels this idea continued. Many modern fluid steel barrels were acid etched to look like Damascus steel.
By removing the forearm you can often tell as they did not always etch the area under the wood. You may also use steel wool on a small spot under the forearm to see if it is real or faux Damascus steel.
Damascus steel was formed by rapping steel strips around a mandrel and forging together. I expect that is why you are confused about "twisted" and Damascus. They are the same process.