gonna go n∞b on you people, but anyway,
we found out we can play around with the
g_weaponarena* options, and interesting game mechanics came to light. setting
g_weaponarena "vaporizer" for example gives us the minstagib gun, with primary fire still instagibbing (or so it seems... no damage setting anywhere), and secondary fire (blaster) having the default damage and push which applies to other players. dandy. what we can see is that there is no apparent way to separate push, splash damage, and direct hit damage, they are all kinda glued together.
interestingly, setting
g_balance_vaporizer_secondary_damage 0 removes the damage and bounce.
setting
g_balance_vaporizer_secondary_damage 1 sets damage to 1, and gives a very powerful bounce that does reliably frag a player against a wall or a ceiling
setting
g_balance_vaporizer_secondary_damage 100 and higher reliably frags player on push.
so there doesn't appear to be a way to remove damage while keeping the bounce, which is kinda what we are after