You can just shop for claws...Visit Anya in Hell and you can buy claws from her. They can spawn with +2 Assasin skills and if you really lucky also +1-3 to Lightning sentry. Of course there's also stuff like Suicide Branch and Wizardspike, but a claw that gives +5 lightning sentry is too juicy to pass up if you ask me.
I found that 2 Bartucs were excellent before I could afford/find/buy from Anya, fast trap laying speed for fire blast, hit recovery, 4 skills combined, awesome. Also, when levelling in NM you can hit them with your claws too. They will keep you going until you can begin to stack the +skills.