Indeed, there is no official model. The easiest thing to do is to is the remove the shield from one of the sword armed Corsairs.
http://www.games-workshop.com/gws/catal ... od1500466aOn here, the guy in the top right corner and the guy on the bottom second from the left are easiest.
Spare swords can be from any models you have lying aroun,d I managed to make some axes by simply attaching an axe-head shaped bit of sprue onto some brass wire. Also the plastic Warg Rider set (not Fell Wargs) has plenty of spare equipment on the sprue, with about 4 swords I think.
Hope this helps.