1d8+DB

Additionally, the traditional leather sap, against someone wearing any kind of armor is just going to get their attention. You could say that against a location that has any kind of protection greater than 1 point, that the black jack only does 1 pt. +DB damage.

Most RPGs tend to tie Skills more tightly to the characteristic: the skill has a governing characteristic, and the level of skill modifies that. BRP tends to use a practice makes perfect philosophy. A character with a DEX of 9 (the minimum required for the weapon) can be a deadeye shot archer, with a skill of 100%+. In say, a D20 system, the emphasis is on innate ability. If you want a good archer, you better have a high DEX to begin with. Practice can make you better, but it won't overcome a lack of beginning talent.

The problem with playing four-color superheroes with a mechanistic system like BRP is the huge range of powers available, from the simply highly skilled, The Dark Knight, to near-gods, like the Man of Steel. For this wide range narrative, systems, like HeroQuest or Atomic Sock Monkey's Truth And Justice give you more wiggle-room. Because, you could, and eventually, see an issue where Spiderman, through some amazing, narrative contrivance, defeats Galactus. Though I imagine BRP would work for most Gamers, who are fine with not playing characters who can reverse time by circling the earth at FTL speed.

That's pretty much how Fantasy Flight's Warhammer40K RPG works. Initial characteristics are 20-25+2d0, generally. Then each skill advance gives the character a +5 skill bonus. Bonuses are figured from the ten's digit, i.e, a strength of 43 would yield a strength bonus of 4.

So, the organization building these portals, are part of the government? Or is that something the PCs have to find out?

I believe that Deus Vult, apparently still available from Mongoose, <http://www.mongoosepublishing.com/rpgs/legend/deus-vult-1.html>, is meant to fill that gap.