Stafford, 32, collected 28 points (nine goals, 19 assists) in 48 games last season with Portland and Hamilton of the American Hockey League. He has tallied 345 points (92 goals, 253 assists) in 610 career AHL games with Cleveland, Worcester, Grand Rapids, Texas, San Antonio, Portland and Hamilton.
The Los Angeles native has also registered two assists in seven NHL games with Detroit, Dallas and Phoenix.
Marshall, 23, recorded six points (two goals, four assists) and 116 penalty minutes in 63 games last season with Hershey and Adirondack of the AHL. He was acquired by Washington from Philadelphia in exchange for Matt Ford on Feb. 2, 2012.
The Boucherville, Que., native made his NHL debut on Nov. 21 vs. Carolina and has appeared in 10 NHL games, collecting eight penalty minutes, with the Philadelphia Flyers. In 216 career AHL games, Marshall has registered 29 points (seven goals, 22 assists) and 316 penalty minutes.
Marshall was originally drafted by Philadelphia in the second round (41st overall) of the 2007 NHL Entry Draft.