on the average, advantage is like giving +2, disadvantage like a -2.
Resistance you were talking about is a +3, then +6 if you went that route.
2 disadvantage is like -4, advantage like +4, so it really is like that, and you don’t have to worry as much about the items this way.
Also, if a weapon is simply incapable of doing something, remember about every roll matters. So if a Pistol can’t do squat against an alien, don’t have them roll. Otherwise it will be harder to explain when they explode and do 50.
- With disadvantage they are going to be less likely to have explosions, with higher armor, explosion is still going to do a bunch.
- With higher armor, once you have equal armor vs equal armor it is going to take forever in combat b/c armor is higher for everyone. Whereas with the (dis)advantage it just becomes equal
Notice, I’m not saying don’t do the armor/extraordinary item thing at all, I’m just saying that isn’t necessarily needed, and you might be creating more work than you need to for accomplishing the feel you want.
To that point, I’m not actually sure what the feel you want is, I’m basing this discussion in Tech Levels, which you mentioned and then seemed to veer away from with extraordinary items. It might do good to talk more about the setting itself, and what you expect the players to be experiencing or feeling during a session.
Right now, it mostly sounds like you want it to be impossible for the players to do anything unless they manage to steal items from the aliens, which sounds hard to do b/c of how much better they are. BUT, I don’t think that is what you want, it is only what I have read so far from a very limited perception on my part. Perhaps you could expand a little more on the setting and what you expect the players to be doing in it.