In the description of Enchanted Throw, I realized that the additional damage done by normal attacks is not listed along with increased skill levels of Enchanted Throw.
That is quite confusing as you can't tell how much better Enchanted Throw x+1 is compared to Enchanted Throw x.
In addition, I leveled Enchanted Throw from 0 to 50 just to see the difference and for me there isn't any. Each white hit does an additional 130k damage for both Enchanted Throw 0 and Enchanted Throw 50.
Each level adds damage to the 'Vengeance Sting' which procs upon getting hit yourself, not the actual throw damage from each basic attack.