My suggestion is to cut backpacks from models of Ironclaw Thwacker, Ironclaw Scorcher, maybe Ironclaw Demo and/or Darkfang Demo. I think there's no need to make it in variety of styles so this is work for about 10 minutes. 20 if there will be difficulties with attaching it to bones in right position.
*Cut Welding mask from Ironclaw Scorcher and/or Darkfang Scorcher.
*My idea is to make a magic book like thoose located all over spiral knights and place it with straps in position of Parrying Blade and/or Side Blade. I think it will be very good looking accesorie for magcian or smone like him. There is a space in magic cloack series just like made for it.
*Another idea is to make belt bag like german warld war II belt bag for misc equipment like this http://waffen.ucoz.ru/_nw/2/67332.jpg in same place as canteen or mirror. That will be great looking with both metal and leather/cloth armor.