In 1.10 of the Expansion the odds of gambling a Unique is 1 in 2000.All blunt weapons (including wands) have +50% Damage vs Undead.You cannot gamble for wands, they must be found.The Sorc-only Orbs should be more useful than wands though, so likely you'll see only Necromancers using wands after a short time in the Expansion.
Sorceresses use them as well in Diablo II, in order to have a one-handed weapon and a shield, and bonuses such as +mana and faster cast are useful for a Sorceress as well as a Necromancer. Wands are not class specific, but they are most appropriate for Necromancers.
