Does having a weapon give you a bonus to intimidate checks if you have one and the target doesn't (or a penalty in the opposite situation.)
I dont think so. Well, Weapon Trick let's you take 10 for Intimidate with a 2H weapon.
In Ultimate Intrigue there's probably some random feat that allows you to exactly what you're asking... it probably has a bunch of stupid prerequisites, though.
If it is a feat, it shouldn't be. But if it is, it definitely shouldn't have prerequisites.
The gm have the last word about this if he feels that the 1 who doesn't have weapon received a penalty it's up for him to decide how much he will receive but in rules there is nothing unless you have a feat or a talent that give you some bonus
The CHAINSAW gives you +2 to Intimidate, but it's probably not availabke outside of Iron Gods =P
The OMINOUS weapon quality lets you add it's enhancement bonus to your Intimidate checks.
You could just pull the Amiri-trick and wield a large sized weapon - rolling lots of dice makes a weapon intimidating.
Or you could tale CORNUGON SMASH or INTIMIDATING PROWESS to represent intimidating someone with a weapon.
Tea cup +12 to Intimidate
The trait Larger Than Life makes you count as one size category larger (for intimidate checks) but only while wielding a firearm.
I guess other kinds of weapons just aren't as scary. :/
Otherwise there are the feats Position of Strength and Improved Position of Strength that basically do what you're asking. But they only work if you have more weapons than your enemy and they don't stack with intimidating prowess.
It also means that because these feats/trait exists it doesn't really exist as a general rule. But they probably should.
