The problem with the Summoner is it's not a Summoning Magic Job it's a Disease Magic Job.
Black Mage's use Black Magic
Whit Mage's use White Magic
Summoner's use Summoning Magic
Summoner's should summon all elemental damage by summoning storms such as fire storm, thunder storm, blizzard storm and tornados. Also we should be able to summon Primals cause unlike Beast Tribes who have a High Priest instead of a Summoner they have to use the summoning ritual to call forth Primals while Summoner's who use summoning magic can summon Primals without the ritual.