What Handicap do you need to be to get blades?

Well, for you I would say blades would work for you. I have hit blades when my handicap was higher and it helped me learn to strike the ball better. I now play a half cavity iron with a thin top line giving it a blade look. It has more forgiveness than a blade that I like. If looks are what you're looking for, give Nike's VR Pro Combo a look. Full cavity long irons, split cavity mid irons, and blade short irons. All have the blade look at address. I play Nike's VR Split Cavity. I've hit the Pro Combos and if the opportunity comes and I can get them, I will. For now the Split Cavity will do. The sweet spot on a blade is the size of a dime so forgiveness is not it's strong suit. They definitely put a premium on ball striking.

whats in your wallet

I switched from cavity back to blades about two years ago and I feel it has hurt my game. I have a slow swing speed and I lost a lot of distance also blades are not as forgiving when you miss hit a ball. A golf instructor explained to me that cavity backs are like your driver the face of the club springs in then out when hitting the ball which helps give you greater distance. A blade does not do that so the distance the ball travels is nothing but the ball and your swing speed. I am thinking of switching back to a cavity back since I am getting older and my swing speed is nothing what is use to be.

Any. When you miss hit the blades you will likely be short of the front side bunkers. Game improvement clubs would likely put you closer to pin high and in trouble.

When you are a scratch golfer. You don't have to play blades if you want workability. You can get those also from Forged Cavity Back irons. For example: Mizuno MP irons.

I would say 3-4 or less. There are some irons that don't have too much perimeter weighting and still work the ball, but really the only people who use blades are the pros.