“I’m a defender”,or “I’m a midfielder” or “I’m an attacker” – “what hockey stick do I need?”

In principle, a hockey stick is no longer position relevant. In the past a defender might want a heavier wooden stick but that was in the days when the defender used to stand at the back of an all-grass pitch with a heavy leather ball and try and smash it to the wingers. The type of stick people use is based on the skills that the y want to execute. If somebody does want to hit a ball more then yes, they want a more head-weighted stick. 

If you're a running defender and want to run with the ball, dribble with the ball, push pass, then pretty much any stick will be reasonable for you. 

If you want to do 3-D skills, which means dribble the ball not only left to right but up and down, you're going to want something that has a later bend
because it’s going to open the face of the stick a little bit more. Imagine if you’re playing golf, a 3 iron has a flat face but a 9 iron has a fairly open wedge face. A 9 iron is something like a late bend stick because the face is open and it’s easier to get the face under the ball and therefore lift it up into the air when you are dribbling. 

If you're a player who executes aerials and drag flicks, then you'll also want something that has a late bend to it.