First of all you go to mdlvis, sellect the ewapon you want to remove and delete it. Now, select the chest mesh and click on sepparate geoset option(green icon). Now you go in magos and hold ctrl + click on the chest geoset you just sepparated. Open the mpq archive and find paladin's texture and right click and select "use this texture"(something lik that, i am on phone now and cant remember).
Now you go to material staff and right click and make a new material and select the paladin's texture. Now opet the geoset window and put the material on the geoset you previously sellected(chest geoset). Now the hardest part you need to wrap the texture to fit the knights mesh.
Giving the hammer and book is easy with simple geomerge, dont know if youre familliar with it.
