Expeditious retreat is useful from levels 1-6, but as psykopeta said, you can find it in Korthos. Since we are on the subject of speed boosts, make sure you have your Phiarlan Pendant of Time before you TR.
Expeditious retreat will speed up your movement when your rune arm is in use, regardless of whatever striding you have. I have 30% striding on - when I use my rune arm, I slow down a lot. When I cast expeditious retreat on top of that, I go faster, but not as fast as 30% striding. I always notice when I don't have it on b/c of the too slow speed. With it on, I can almost keep up to parties.
Be careful crafting extra's onto rune arms(unless you have 2), did it with my only hand of the tombs which is ml13 now!
You cannot replace(disjunct) them once crafted unless you buy something from ddo store forgot what its called.
Also you can make some nice collars from handwraps even named 1's (upgraded stonedust handwraps/Collar) in a device workstation.
Actually you can disjunct rune arms without buying anything from the store , just go to a device workstation and put the rune arm in it.
You just have to use a dust of disjunction.
I however enjoy Masterful craftsmanship and ranged alacrity crafted on mine.