Made a suggestion akin to this actually.
http://star-made.org/content/split-engines-different-types-different-effects-also-add-item-levelstiers
Specifically, the second part involving item tiers, of which I believe 3 would be best. Upgrading would essentially be done by removing the old blocks and replacing them with the more expensive ones, once you could afford them or are able to produce them in a factory.
That said, the general idea behind splitting the engines into different item types for different things could be applied to weapons as well. Perhaps have one block type that acts as the point a weapon fires from, and a couple others you stack together attatched to this to enhance the attributes you want. It would if nothing else help in cases where to get the weapon you want you have to make it shaped in a manner that clashes with your ideal hull shape.