ummm, i see you shot it at f/1.8, maybe stop it down to 2, or even 2.8. also, is it a soft image straight off the camera? because i know i've had sharp images go soft between the resize and uploading, so to compensate i oversharpen before the resize sometimes, and then sharpen again to perfection + a little and then upload.
lots of people recommend a large contrast area sharpen (not sure of the terminology here, but a larger pixel unsharp mask or smart sharpen) + a second pixel to pixel sharpening, or a smart sharpen with smaller pixel setting. I'm sure someone else can describe it better and more accurately, thats just what works for me.