Me and my friend split 3 Core Sets. It was all great value, but we ended up with 3x Kari and 3x Ardus. So me being the Daqan player traded one of my Kari models for a Ardus model.
I am not very comfortable with using Greenstuff, so I wanted to do some very simple conversions, without using any Greenstuff. I knew that I wanted to make him into a Champion Upgrade Figure, to use with the Daqan Spearmen Unit. In order to make the model look as similar to the official Champion figures, as possible I wanted to use a bald head and make sure to keep Ardus dual wielding. What I ended up doing was cutting off Ardus head, weapons and all Spikey bits from the model.
I replaced his head with a Space Marine Sergeant head(slightly modded to remove minor cybernetics) and his weapons with a Space Marine Combat Knife and a Clansman´'s Claymore(From Warzone Ressurection).
The picture below gives you an idea of what it looks like, even if the quality of the picture is not the best. Kari to the side, for scale.