I you are asking yourself if you need a more aggressive razor or perhaps a sharper blade then you are probably running into a couple of different issues. If you are feeling pulling and tugging while you shave, and having to apply pressure while making your passes, then you probably need a sharper blade. If however, by the time you get to your final passes the blade is scratching and irritating your skin, and applying alum bloc causes you to scream, then more than likely your blade is too sharp. On the other hand if you find yourself having to make repeated passes over the same area, and the blade doesn’t feel like it is making proper contact with your beard, then you may be dealing with a razor that isn’t aggressive enough for you. A razor that is too aggressive for you will remove a lot of hair in a single pass, leaving your skin feeling irritated and burning. Of course none of the above is irrelevant if you didn’t prep for your shave properly.
However, like most things in classic wet shaving, you need to figure things out, which of course requires some trial and error (and fortunately or unfortunately depending on your point of view, at least a couple of razors). Your best bet is to start with a razor that has a middle of the road aggressiveness to it, something like the Edwin Jagger 89lbl or any of the Merkur razors with a safety bar, like the Merkur 42. Once you have your razor you can start to eliminate blade brands knowing that a Feather Blade will be ultra sharp, a Derby blade will be mild, and a Shark blade will be somewhere in the middle. Once you have experimented with a few blades (you may want to consider a blade sampler) you can start pairing different blades with different razors. For example using a Derby blade with a Merkur 37C – which is an aggressive slant razor, or perhaps a feather blade in a less aggressive Wilkinson Sword Classic razor.
You may find a perfect match straight away and not have to experiment with different combinations of blades and razors, although I will have to say that part of the joy of classic shaving, at least for me, is trying to find that perfect blade / razor combination. If you don’t hit the perfect combination right away; trail and error, along with a bit of education will get your the result you are looking for from your double edge safety razor and blade.