This week I'm trying out my 'new' razor - the Gillette "Khaki" Old Type - and is so far quite enjoying the experience.
The blade I'm using is rather different both in alloy and in shape from what the US Doughboys would have tucked away in their dopp bag as they were deposited into the maelstrom of mud and horrors that were the trenches of the great war...
The alloy was mild carbon steel, and there was three more-or-less circular holes. The old school blades were also thicker than the blades used now, which probably to some extent affects the perceived aggressiveness of old razors by dint of altering the blade angle slightly.
Today's blades are commonly made out of stainless steel, and have a single elongated hole shaped to fill all DE razors (not just the three piece razors).