the only time you should run a sage in arenas is with a dedicated team, even more specifically you should be running with a fully geared min/max tank, since guard gives us a fighting chance. i mostly do reg warzones with group ranked mixed in, but i almost never solo q ranked because i have horribad luck when it comes to the matchmaking system and am often left without a tank. but as far as arena enjoyment, i like a few arenas here and there, im not a huge supporter but class balancing will progress even if its not as fast as some people want, but eventually (and hopefully) sages/sorcerers will fit in arenas better. but honestly, i cant say ive felt extremely underdeveloped compared to other classes, i can still top dps, get most kills, most healing, but like you pointed out earlier.. you should only be running with a team.