Stranded steel cable?

There are cable cutters that are made for this. If you compare wire cutters to hedge pruning shears, you'll notice most wire cutters are what is called "anvil" style, the edges butt together to cut the wire. Cable cutters that work well for this are of the "bypass" style where one blade passes by the other, like scissors.

I personally tend to wrap a turn or 2 of electrical tape around where I want to cut, and use a dremel with a fiber reinforced cut-off wheel. Cut thru the tape and the wire, and the tape helps prevent fraying. I do this because I have a dremel and am too cheap to buy the correct cutters.

Since you'll likely need to solder an end on the wire, you can also "tin" (soak with solder) the spot where you want to cut. Then you can cut it with any decent wire cutters, and it'll cut without fraying, as it's all bonded together there.

J