More like this:
Orc and human, both with broadswords, both with 100 OBs.
Human is a PC, Orc is an NPC.
Combat starts, human and orc are 20' apart, out of "Melee Range". (Short of treachery, ambush or surprise, many combats should start outside melee range.)
Both the human and the orc have weapons drawn, so at the start of the combat, they are in "Combat Stance". Both must declare OB/DB on round 1 before the initiative.
GM writes note: Orc is aggressive, but not insane, 75/25
PC says: My character is neither passive, nor aggressive, so 50/50.
This is just a default OB/DB split to begin combat. (If you play the angles more than staying in character, likely you'll choose 100% DB every time.)
Initial Declarations
Both the Orc and the Human intend to melee, if the PC wants data on the Orc, I might allow a free perception check (Or perhaps a "melee as lore" check), in a more complicated situation I might require a "Quick look" 10% action to do so. So perhaps the human knows "The Orc is looking rather aggressive, but is not going full out without concern for defense."
Of course, the moment either the PC or the NPC declare an attack, they again need to declare an OB/DB split, which takes affect immediately. (So the orc could switch to 100% OB, or 100% DB.)
Then roll initiative.
Then attacks.
It's a bit Stratego. . .the whole "I go full OB" to discover they also went "I go full OB" can suck if you loose initiative. (Kicks butt if you win).
It's supposed to simulate the fact that you can place yourself into an overly aggressive posture and get yourself killed, or not be aggressive enough an miss a golden opportunity to take out your opponant. . .short of precognition or mind reading, it's hard to predict your opponant's actions before making decisions like that. Do you really know how aggressively your opponant will attack, or are you just capable of making a guess based on their previous pattern? (And if you've never fought them before, who knows?)
OTOH if the problem is that the players FEEL like the GM is taking advantage by declaring last, you can have the GM declare first, via a hidden note to themselves, then the players declare. That should cull that ptoblem.
Frankly, if you play any roleplaying game with declare/initiative/action being the sequence, I urge you to try out this experiment for one combat:
Have everyone do hidden declarations by writing them down, including the GM.
Oooh, wow, it's amazing how people will bunch up, with half the party attacking one target. . .or how they jam up in a doorway. . .or how 4 people dive to pick up the sword the villian dropped.
Anything short of "Hidden declarations" is a mild form of the players acting via hive mind. . .each player usually will fit their actions around what's already declared. Generally, that hive mind makes the game run more smoothly and usually makes it more fun. (Though, hidden often makes it more funny).
Roping all the NPCs into the mix too, so that the GM needs to publicly declare all actions of the NPCs before the PCs declare, is extending the "Party Hivemind" out to almost "Precognitive Omnicient Party Hivemind."
I've often felt that in terms of that kind of stuff, the less you know the better. . .it makes the choices harder and the combats more tense, making victory that much more rewarding.