As far as regular efficiencies go, without Monodexterous Casting they're limited only to staffs for their melee weapons (Which are pretty weak). With it they can use light one-handed weapons, such as daggers, certain swords, clubs, axes, whips, etc. If you you do want a more melee-focused Warlock Mage, you could try to make due with Avatar Abilities. Maybe have one of your abilities allow you to charge your magic damage through your staff, or conversely turn your magic damage capability into a sort of personal barrier so you can wade into the thick of melee. 

As a Warlock you could use your summoned demons to try to go for a fusion type mage, someone who eschews weapons to take on the aspect of their demon. Of course that'll only last as long as the demon will, which is a few minutes at most.