My experience with canes and wands was thus.
+1 Elm/Ash Cane - +3 Magic Potency / +6ish Magic Accuracy
+2 Elm Cane - +6 Magic Potency / +12~15 magic accuracy
It isn't reflected in the item tooltip, you have to look at your stats and see how much is being added to notice the difference.
WoW Blackhand-US-Date of Retirement: 9/21/2010... /Sigh
Devari - 90 Rogue 85 DK Druid/Mage/Warrior 70+
FFXI - Shiva "Retired.... Or not? One more try, honest."
Desmar - 65 Sam 36 Mnk 18 Thf 12 War
FFXIV - Devari Garamond - Sargatanas 50 Paladin / Culinarian / Weaver / Armorer
Beta - Devaria Ariadne - Ultros - Pugilist