LuckLuck determines critical hit chance vs. glancing blows. Glancing blows are the opposite of critical hits; they are critical failures. The lower a Summoner's Luck, the more erratic their attacks and heals will be as they will have a higher chance of a "glancing blow" which hits for very little damage or heals for very little health. While not as important as other stats such as Intelligence and Perception, Luck should never be ignored.
Perception
Perception is a primary stat for a Summoner. It decreases a target's ability to resist a Summoner's Magical attacks.
TIP: Also another stat that affects a Summoner's Minion; it increases their Expertise.
Intelligence
This is an important stat for Summoners. Intelligence increases magical damage and healing.
Conviction
Conviction affects a Summoner's control spells, both duration and chance to hit.
TIP: Willpower increases a character's chance at resisting control effects.
Faith
From the Healer's guide:
Faith determines a healer's ability to penetrate wounds. Wounds are accrued during combat and the more wounds a character has, the less effective healing will be on them. A higher faith will allow a healer to penetrate wound complexity and have more effective heals.While not true healers, this is quoted here as Summoner's can be built to do a lot of healing
Wisdom
Wisdom increases total mana pool and mana regeneration. Also, it affects the Summoner's Minion and their finesse.
TIP: Finesse represents the resist chance that an enemy will have against a Minions physical attacks.