The Ruffian rogue racket says:
You use whatever tools you have at hand to get the job done. You can deal sneak attack damage with any simple weapon, in addition to the weapons listed in the sneak attack class feature. When you critically succeed at an attack roll using a simple weapon and the target has the flat-footed condition (unable to focus on defending itself), you also apply the critical specialization effect for the weapon you’re wielding (page 283). You don’t gain these benefits if the weapon has a damage die larger than d8 (after applying any abilities that alter its damage die size).
The Unconventional Weaponry feat says
You’ve familiarized yourself with a particular weapon, potentially from another ancestry or culture. Choose an uncommon simple or martial weapon with a trait corresponding to an ancestry (such as dwarf, goblin, or orc) or that is common in another culture. You gain access to that weapon, and for the purpose of determining your proficiency, that weapon is a simple weapon.
Can a human Ruffian Rogue with the Unconventional Weaponry feat benefit from Sneak Attack with their unconventional weapon?
The Ruffian's sneak attack requires a simple weapon, and the Unconventional Weapon uses simple weapon proficiency, so the two features should be compatible, right?
Best Answer
No
All weapons have weapon category (pg.279) such as simple, martial, or advanced. Weapons also have other traits, such as agile. The Rogue sneak attack feature (pg.181) requires the use of either:
As you said, the Ruffian racket also allows you to sneak attack with any simple weapon.
A weapon you utilize through the Unconventional Weaponry feat can only be used with sneak attack if it fits into one of those categories. Unconventional doesn't change the weapon category, it only changes how you calculate your proficiency.
So no - it's not true that any weapon accessed through unconventional weaponry qualifies for sneak attack, because it's not automatically a simple weapon. However, if you choose an uncommon simple weapon (such as a clan dagger or katar) you can use it for sneak attacking.