I have a 55 sk and the focus effects I think you might want are mana
preservation, burning affliction, and extended enhancement items.
Everyone who can cast a spell wants mana preservation, and extended
enhancement will make what few self buffs sk's have last a little
longer, burning affliction will make those damage over time spells do a
little more damage, and since we all know sk damage over time spells
are just lower level necro spells you'll need all the help with them
you can get, and some of them do actually help hold aggro too.

My suggestion for a low level sk weapon is Mace of the Shadowed Soul,
which you can usually find in bazaar at some really low price since
they are a common drop and only sk's can use. Base damage on that is 19
and gives you +10 int. I'm sure there are plenty of weapons you can
find in bazaar when you have more plat to spend, but I suggest that
mace because it's rather cheap and sometimes people even give them away
because as I said they are common and only sk's can use.