Financial terms of the deal, announced Tuesday, weren't revealed.
The 23-year-old Galiardi played only 35 games last season because of wrist and forearm injuries. He finished with seven goals and eight assists. The Avalanche selected Galiardi in the second round of the 2007 draft.
Rissmiller, 32, played for five teams last season, including the Lake Erie of the American Hockey League. He was originally signed by the San Jose Sharks in June 2003 and has played in 192 NHL games.
You know what? We've played in some pretty special buildings along this playoff run so far. You start in Detroit, you go to Montreal, you come here … I think it's the first team to beat three Original Six teams to get to the Final if I'm not mistaken. That says how tough the road has been. Those are tough places to win.
— Lightning forward Steven Stamkos after Game 7 win vs. Rangers on Friday in New York