Thanks for posting the photo. I took a look at the example and found a couple things that might help. As is typical of wide angle lenses like the one you used, there is a lot of chromatic aberration. Most RAW converters these days support correcting that during processing.

Also, there appears to be a decent amount of in camera sharpening. It's possible that it's being compounded by jpeg artifacts, but the unprocessed photo you posted already has a lot of halo'ing going on. What are the in camera sharpening settings set at? Have you tried lowering the amount of in camera sharpening and taking full control of it yourself via photoshop?

The image you posted, on a scale of 1 to 10, probably ranks a 7 in terms of how sharp it is. The combination of CA and Halo'ing in the unprocessed image makes further sharpening more challenging.

I'm not familiar with your camera so can't offer any specific recomendations.