I'm trying to slice this model: https://www.shapeways.com/product/VVNUVZ6JL/dread-warrior?optionId=66361748&li=user-profile
I'm using a .4mm nozzle and .1mm layer height. When using slic3r some of the layers seem to just not get generated. You can see this on the horns. It also has some weird artifacts on the shield of the model.
I tried using Cura to slice the same model and while it does a better job for the horns it removes most of the face on the model.
Are there any slicer settings I can adjust to help fix these artifacts? Is there any other slicer out there that may fix the problems? Is this just a problem of needing to use a smaller nozzle and lower layer height?
It's a nozzle size issue. The model contains a lot of details which is really challenging to print with a 0.4 mm nozzle.
A big nozzle is just not able to print such fine details. You should switch to 0.25 mm or 0.15 mm. Just try to set a smaller nozzle in your slicer.
There is a nice article on Prusa's blog showing the difference in printing details with 0.4mm and 0.25mm: EVERYTHING ABOUT NOZZLES WITH A DIFFERENT DIAMETER, especially chapters Examples of practical use and Printing miniatures.
See the difference: