It came up multiple times in a single three hour span or so on another forum I frequent, so I put this together. I'm posting this guide to be useful, so if you note anything I missed, let me know please.
https://docs.google.com/document/d/1..it?usp=sharing
The Dexterity to Damage List
There are eleven ways I know of to get dex to damage. This post is an info post for everyone who keeps asking about it.
To get it out of the way: One of those eleven is the fifth level of Gunslinger and most of its archetypes, which grants dex to damage with firearms (and in one case, crossbows).The second is the fifth level of the Raging Technologist Barbarian Archetype.
now then:
#1 - The Agile weapon enhancement. This +1 enhancement can be placed on any finessable weapon, and from that point forward you may add your dex mod instead of your strength mod to damage.
#2: Dervish Dance - This feat is for scimitar only. Cannot be gained earlier than second level because it requires two ranks in perform dance, except by Bards with the Dawnflower Dervish archetype. Treats Scimitar as a one handed piercing weapon, add dex to atk and dmg.
#3: Mythic Weapon Finesse - only available if you have mythic. Allows the character to add dex to damage to all finessable weapons.
#4: Slashing Grace - came out with swashbuckler in ACG. Applies dex to damage to any single light or one handed slashing weapon, but does not make them finessable. It makes them treated as One handed Piercing weapons. This means that if you have one level of swashbuckler you can use dex to atk and damage with that weapon. - Errata caused this feat to be slightly less awesome, as you are required to have your off-hand completely empty and doing nothing at all.
#5: Fencing Grace - gain dex to damage with rapiers, which are already finessable. - Errata struck again, but arguably as it was simply a reprint some players might succeed in a case to specifically use the version from Advanced Class Origins, which does not require an empty and unused off-hand.
#6: Fourth level of a swashbuckler archetype called Whirling Dervish. Interestingly, applies to ALL weapons that work with Swashbuckler finesse, + scimitar.
#7: The third level of the Unchained Rogue (and the 11th and 19th levels) allows one to select a single finessable type of weapon. The rogue may now use dex to damage with that type of weapon.
#8(bit out of order): Second level of the Swordlord prestige class allows you to add dex to damage with an aldori dueling sword.
#9 Starry Grace - Gain Dex to damage with a Starknife
I know of only one way to make a one handed weapon count as a light weapon: Effortless Lace from the Giant Slayer's handbook, which causes any one handed piercing or slashing melee weapon sized for the wielder to be treated as light for purposes of weapon finesse and any feat, spell, or special weapon ability that can be used in conjunction with light weapons. It costs 2500gp and it is one use only. It affects a single weapon for as long as it is attached, but if removed loses all magic.
Note that order is effectively(though it may not be exact) chronological by release date, not by power, ease of use, or other criteria.