Right, comparing the strike-half of Counterstrike to Strike when paired with various actions, there are ups and downs:
vs Strike: Weapon Skill -1d (minimum you can allocate to the Block half) vs Ob 1
vs Block: No action
vs Feint: No action, plus you get hammered on
vs Strike: Weapon Skill vs Ob 1+advantage
vs Block: Weapon Skill, subtract advantage, vs Block successes
vs Feint: Weapon Skill vs Ob 1+advantage, opponent takes no action.
Now, obviously you’d have to observe a lot of fights and count actions to determine which is actually better, since it depends on how often people tend to script each action. But obviously there are situations where Counterstrike is a bit better (when they try to hit you while they hold the advantage), and situations where it’s always worse (when they feint) and situations where it probably doesn’t matter much (if I’m blocking while you’re at +4Ob, you aren’t gonna hit me. Now, you’re better off with a Strike so you can log that juicy Knife test, but just in terms of the fight it doesn’t really matter).
In a real knife vs spear fight where my dude was outpositioned, I wouldn’t be at all worried about whether to script Strike or Counterstrike. I’d be entirely focused on how I could Beat, Disarm, Charge, get to the inside, or use the environment to even the odds.
In a more likely +1 or +2Ob situation, I don’t think I’d be going “Okay, I want to hit him, so I script Strike. Only I’m at a disadvantage, so then I automatically script Counterstrike instead, since that’s the better way of hitting when you’re at disad.” Looking at the table, if I script Strike I’m testing my B5 Shiv skill against Ob 2 for anything but a Block, Avoid, or Counterstrike. For those, I’m likely to miss (except against a highly offensive Counterstrike, where my opponent gets few successes on defense). If I script Counterstrike, I’m not hitting against Feint, Charge, or Throw (which were good bets with Strike) or Counterstrike (which was a maybe, and probably involved getting hit myself so we’ll call that a wash). I’m losing my chance at beating a Block or Avoid. Beat is unlikely, since it’s useless to my opponent. Against Strike, Great Strike, Disarm, Lock, or Push, I can test 4d against Ob 1 (which is better odds than 5 vs Ob 2, but not by much).
It’s also worth noting that I’m actually better defended during the Strike than I am when I counterstrike with all my dice: It’s easier to hit someone rolling 1d for defense than it is to beat Ob 1.
If I was trying to decide between Strike and Counterstrike anyway, this is maybe a point in Counterstrike’s favor while at a disad. But if I was trying to decide between Strike and Lock, this wouldn’t make me swap that for a Counterstrike just because of the disad.