Both guards played less than 20 minutes in the blowout, which saw Richmond score the first 12 points of the game. The Flames trailed 41-21 at the half.
Brothers shot 7 for 10 from the field, including 4 of 5 on 3-point baskets. Brothers has made 131 career 3-pointers and needs 23 to crack the Spiders' top 10.
Forward Derrick Williams grabbed 11 rebounds to go with his 8 points for Richmond, which shot 29 of 59 from the field.
Big South member Liberty, which is coming off a 14-18 season, was led by Davon Marshall with 12 points.
The victory was the Spiders' 13th season-opening win in a row.