...never see another staff for ~9 levels. NPC Merchant has every weapon but no staff. Search reveals a dropped staff is in game ~ level 7. Somewhere. Early quest offers wand, but no staff...
Warlocks are currently designed to favor wands over staves. It's a benefit rather than a limitation: offhand daggers unlock at level 36, and early 1h wand use ensures your weapon skill is already leveled by then. That said, if you prefer staves, there are enough options available (quest rewards, for example).