you can use a portable bandsaw to cut rebar, I find it to be the best solution when I can't take the rebar somewhere to cut it. But be careful if the metal is heavy it could fall and dent/damage the floor if you're working indoors of cause injury should it land on you.
Use a third blade, preferable mounted to your utility handle, to part them. Handle only from the back side and give the utility knife a slight twist as soon as it is between the points of the new blades.
Pipe cutters are really useful tools that can be used in the house to cut pipes that are made from metal or plastic. You could always try using a saw of some kind but pipe cutters will give you a much straighter edge.
Here are some basic instructions to help you successfully use a pipe cutter.
1. Decide exactly where on the pipe you would like to make a cut.
2. Loosen the handle on the pipe cutter and place it around the pipe.
3. Now tighten the cutter until the blade is in contact with the pipe.
4. Turn the pipe cutter a few turns around the pipe and it will score a line into the pipe.
5. Keep turning the pipe cutter around until you've cut the pipe off.
6. In order to create a nice straight edge inside the cut pipe you need to take the bottom blade out of the pipe cutter.
7. Place it into the cut end of the pipe and turn it around a few times until it's nice and smooth.
This utility knife reassemblies similar to the original. The only difference is this model uses two screws and that plastic insert. You will align the two metal halves and bring them together. Use care that the blade does not fall out of its holder and the little black plastic piece stays in place, near the blade. This may take a few tries. after you bring the two halves together you will carefully separate the bottom end (farthest from blade). Separate it just enough to slide the plastic insert into position. Once the three pieces align you will know. With little effort the two metal halves will close together. Install the two set screws and test for proper function. I'm including a Youtube video that shows how to properly change the blade and what it will look like after it is reassembled. https://www.youtube.com/watch?v=5napTSRSyeQ