Third person characters can not pick up weapons and ammo, as the wizard is the only character 100% compatible with third person mode. It only contains the staff and fire ball, hard coded into the engine. This feature is not implemented yet. Sorry.
DLC and updates will be released to have more third characters and weapon choices in the future.
Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz, 2400 Mhz, 4 Core(s), 4 Logical Processor(s), 8gb RAM, Nvidia gtx660, Windows 7 Pro 64bit