Cell border on cell value

You can do this with conditional formatting.

You would format the upper left corner (in your example, A1) to have a top and left border if C1=1. Similarly you would format:

B1--top and right
A10--left and bottom
B10--right and bottom
A2:A9--left
B2:B9--right

Use the same strategy for A10:B20 for C1=2.

(Excel does not let you apply conditional formatting to a range of cells for an outside border around the entire range, according to my experiments. When I select an outside border, it applies it to all cells in the range individually, which is not what you want.)