For a support focused character I would personally consider perception and charisma. They give you some nice additional ways to support your group/guild, in addition to supporting them with your spells. With PER and CHA you will be able to help with fantastic skill of mysterious item identification, NPC interaction on behalf of your group, controlling higher amount of pets which can also be of use, spotting hidden things in world, extra skill in finding valuable resources, charming creatures which could also be helpful, etc.
Below is Spotlight description of what PER and CHA are. Take a look. Might be an interesting option for your support character. 
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PERCEPTION
Perception is a measure of the accuracy and observation skills of a character, determining its chances to score critical hits and the damage they do, its accuracy rating, its ability to instinctively identify items, to spot hidden creatures, traps and treasures and to find valuable resources while gathering.
CHARISMA
Charisma is a measure of the leadership and mental abilities of a character, determining the amount of pets and companions it can control at once, its ability to charm other creatures and its affinity with mental abilities, which increases psychic damage and psychic resistance. It also grants a moderate bonus to item identification, makes interactions with NPCs easier and more effective, and determines the base luck of the character.
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Udoadra also has affinity with charisma (+3) and perception (+1) making it very worthwhile investing in those, since you get more points like that then investing in other attributes.
Just max those 2 attributes as much as you can, and in small chance if any unspent points are left, you could buff constitution a bit to increase your survivability.