You can get ability graphics from the ability skill functions.
I use them to get the level 1 ability graphics for crafting for the tradeskill node gathering.
This is how I get the crafting skill ability graphics,
Lua Code:
local abilityIndex = 1
local skillType,skillIndex = GetCraftingSkillLineIndices(CRAFTING_TYPE_ALCHEMY)
local skillName,skillRank = GetSkillLineInfo(skillType, skillIndex)
local abilityName,abilityIcon = GetSkillAbilityInfo(skillType, skillIndex, abilityIndex)
You would just need to grab the skillIndex and skillType for the other abilities you need using the functions available at :
http://wiki.esoui.com/API#Skills and then find the match to the abilityName in the spell. I use the above for each of the tradeskills and place the names and icons in a table for later use. That might not be as useful for what you need but maybe a function to call that extracts the icon for the type,skill and ability and rank you are looking for.
It is possible that abilityGraphic integer value is the abilityIndex. But I haven't seen a function that grabs the details from an index. Surprise surprise.