A foot or more long, and a couple of pounds. The large end of the straight part might have bare steel where the key is inserted. Remainder would be hard vinyl coated, not that it makes a difference. War hammer is an accurate comparison.
The W and I have those same locks for our bikes. Someone comes swinging one of those things at me, they're going to spring a leak or two. No way you want to take a hit to the noggin with one of those things.