I made my son a Mine Craft cake this weekend. It was a "grass block" with a sword coming out. The sword is straight up. There are just a couple inches of sword before the handle begins (above the cake). A Mine Craft sword is not thin. I made it from RKT, but found that it didn't want to stand up. The RKT wanted to bend and sag. I ran skewers through it and ended up having to have three behind it to hold it up. It was probably an inch thick. I find that I learn new tricks with every cake, but this one, I'm having trouble imagining how I might have done it differently....suggestions?
When I have to have something heavy sticking out of a cake, I make the cake board thick and hammer the dowels through the cake and into the cake board.
I would probably make the sword out of gumpaste. Another thing I do to make RKT stronger is to run about half the rice crispies through the food processor. This does make it more dense and heavier though.
I would make the sword out of pastillage. It dries rock hard (can be cut with a saw or Dremel and can be sanded) and should stand up for a long time, at least until the cake is eaten.