Below is the list of all affixes obtainable from obsidian. You cannot obtain Weapon Damage from Obsidian or Ruby (drop only).
Crystal Affixes
Attack Speed
Reduced Cost
Reduced CD
Crit Chance
Crit DMG
MP Regen
HP Regen
Gold Find
Luck
All Resist
Total HP
Total MP
HP On Hit
MP On Hit
Armor
Dodge
Block
Crushing Blow
Deadly Strike
Weaken