Let's make two assumptions first (and hope they are correct!)...(1) the slabs have been designed to accept the anticipated loads, and (2) you are only talking about a perimeter handrail, not an additional balcony (separately loaded) to bear on the existing slab.
Now the issue is one of designing and anchoring the handrail. First the handrail has to withstand a lateral concentrated load by most codes. Further, both a lateral distributed load and vertical distributed load must be accommodated by most codes. Don't forget to check the wind load...it can be significant, particularly at upper elevations and near coastal applications. Don't forget the little things like picket spacing...must typically comply with a life safety codes as well as building codes.
Next consider the materials for the handrail. If aluminum, be careful of dissimilar metal contact, contact between the aluminum and the concrete, and "electrical" continuity between the rail, the fasteners, and the reinforcement in the concrete. If steel, less problem, but still a consideration.
Then comes the anchoring....wedge?, epoxy?, embedment?
All will work, just different considerations for each. Near the edge, wedge anchors have lower capacity than epoxy anchors because of compensation for "blow-out" at edge. For rail post embedment, be sure not to trap water or even condensation in the post or on the surface surrounding the post. This will lead to corrosion and premature failure. Horror stories abound, including death!