Weir added the 33-year-old former Birmingham striker to his squad on Wednesday on a deal until the end of the season and wants more reinforcements as the Blades aim to shake off a terrible run of form.
They are boosted by the funds of co-owner Prince Abdullah and Weir is hoping to get a new player in, but does not know when he will get the deal over the line.
"We are working on possibly doing something else," Weir said. "We can't comment on individuals but we are trying to strengthen and we are working on it as we speak.
"These things change all the time so we can't put a timeline on it."
Meanwhile, the Blades will still be missing Jamie Murphy for this weekend's visit of Preston.
The winger has sat out the last three games with a groin injury and Weir admits they are still trying to identify the cause of the problem.
The Blades boss added: "Jamie is struggling. We are hoping to get to the bottom of it and get him on a programme where he can be back contributing and really helping us.
"He has been out for a couple of weeks and we are trying to get to the root of that problem."