I dunno what the respawn value was yesterday. Today when I looked at the server config file, it definetely was 25 sec
The only way I see in the default configurations (which lists all Nexuiz custom cvars) to configure the weapon respawn delay is g_pickup_respawntime_short, and this affects items as well (as I posted above). I don't see a way to influence weapon respawn delay only (or weapon + ammo respawn only)