Sledgehammer?

[Fist2Jaw]

So I had a discussion a while back about what category of proficiencies Improvised weapons fall under. Never got a definitive answer, cause I got a Makeshift Scrapper who could use a decent weapon. He's unchained and I know they're more dex focus, but the flavor of my campaign limits the amount of "Real" weapons we could find, so I improvise. And as fun as hurling beer bottles at my enemies, I was wondering if my makeshift scrapper could use a sledge without any penalties?

[SyrioForel]

I would let it fly if you had no penalties for improvised weapons, because it would be weird if you could wield something that wasn't a weapon better than something that was...

[Bear Burning Ashes]

A Sledge would probably act as a two-handed bludgeoning weapon and deal 1d8 damage.

Once you grab Improvised Weapon Mastery it'd bump up to 2d6 (same as an Earthbreaker).

[Skylancer4]

SLEDGE
Price 1 gp; Weight 10 lbs.
This heavy, two-handed hammer is normally used in carpentry and other construction tasks, and is also useful for driving in tent stakes to help secure campsites in areas with strong winds. If used in combat, treat it as an improvised earth breaker (see page 27).

Improvised Weapons

Sometimes objects not crafted to be weapons nonetheless see use in combat. Because such objects are not designed for this use, any creature that uses an improvised weapon in combat is considered to be nonproficient with it and takes a –4 penalty on attack rolls made with that object. To determine the size category and appropriate damage for an improvised weapon, compare its relative size and damage potential to the weapon list to find a reasonable match. An improvised weapon scores a threat on a natural roll of 20 and deals double damage on a critical hit. An improvised thrown weapon has a range increment of 10 feet.

What exactly are you questioning? They aren't under any proficiency unless they are stated to be or treated as such (such as in the case of the Scabbard, combat). The feat Catch Off Guard removes the penalty for using melee versions, the weapons don't fall in any "proficiency" however. That is kind of the point of "Improvised" weapons, you find an approximate weapon to get stats from, but they aren't that weapon.

[Fist2Jaw]

My question Skylancer was essentially "Could my rogue with Catch Off-Guard use a Sledge hammer as an improvised earth breaker without the penalties for not having martial weapon proficiency earthbreaker?". I suppose the answer is "Yes, you can use it without Martial Weapon Proficiency: Earthbreaker", and I wanted to double check.

[Skylancer4]

Yeah, Improvised weapons don't have proficiency but the other side of that is they don't benefit from things like weapon focus of the the like.

What they do allow you to do, is pick up some random item and make it an effective weapon. Basically Catch Off Guard is the effective proficiency, because it is what removes the penalty that you would normally receive for using it.