Is the Sigma 85mm f/1.4 EX DG HSM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 85mm f/1.4 test image. Observe the contrast and resolution of these results.
Is the Sigma 85mm f/1.4 EX DG HSM Lens set to 85mm f/1.4 sharper than the Nikon 85mm f/1.8G AF-S Nikkor Lens set to 85mm f/1.8? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.