Need a 54 degree wedge , still don’t really understand these clubs and which to get

I have a 50 and a 58 , I use my 58 for everything around a green but I don’t understand all the grime and bounce, they are just two vokeys I got given

What should a golfer be looking for when buying one? I suck so I will only be buying a used club and not be getting fit but still want an idea of what to buy.

I play in the UK on low end courses for now that don’t always have the best greens and fairways