When choosing a race for your shadowknight there are two common schools of thought. There are three steps of small race shadowknights. Erudites have very poor melee skills countered by the highest level of intelligence. Dark elves feature probably the best mix with slightly below average melee skills countered with very high intelligence. Iksars have middle of the line stats but have the advantage of regeneration.
Humans are middle ground with no attribute being above or below average.
There are some who will tell you that intelligence is not important to a shadowknight. The reasoning behind this is that a shadowknight's do not generally expend a large amount of mana in a battle. In a typical dungeon battle you will most often cast your debuffs or dot's. Since our primary damaging spells are dot's we only need to cast each spell once per battle. While the above paragraph is completely true it does not tell the whole story.