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.
[He's] real confident with the puck now, getting it off his stick quick and no second-guessing. We need that. He's such a good guy in the room. He works so hard. That's the big thing. For not a big man, he just fights for every puck and when he scores, the guys appreciate that even more.
— Winnipeg Jets coach Paul Maurice on Mathieu Perreault, who scored two goals in win against Chicago Blackhawks on Tuesday