
NoxiousMiasma |

Nah, Phoenix is a Bard , actually - he's actually way more reliant on bluffing and persuasion to then use a piece of evidence to catch a witness in a lie and force them to cop to the actual truth. Plus he's a total theatre kid! I'd put him as an enigma muse bard, heavy on the investigative and utility spells (cross-examining a witness's pet parrot is probably slightly less nuts on Golarion than Earth...), and a surprisingly high Con and Fort (guy face-tanks some pretty ridiculous stuff... might just be dice luck though).
There is actually an Empiricism Investigator in AA, though it isn't Phoenix. Miles Edgeworth is actually the investigator, focusing on how witnesses might lie, but the evidence never does.

YuriP |

Objection!
Phoenix Wright isn't a bard he doesn't uses performance for nothing and bluffing and persuasion is something shared between all attorneys. A main part of the game is to search and collect evidences and uses them to explain how and the order that the facts happened. OK that many times it receives some help from Maya and others but usually this all are tools to help him to empirically understand and describe the events to save its clients.

YuriP |

About feats that the OP asked for the build:
Empiricism/Interrogation Investigator
Str: 0
Dex: +1 (+1 from free)
Con: 0
Int: +4 (+1 from ancestry, +1 from background, +1 from key, +1 from free)
Wis: +1 (+1 from free)
Cha: +3 (+1 from ancestry, +1 from background, +1 from free)
Intelligence is the basis for the char both from being the key stat and from be the primary ability needed to get evidences, create arguments and point the facts.
Charisma to allow it to press testimonies and to get info from them while investigating.
Wisdow due perception (but only due this Phoenix Wright doesn't look to be wise many times).
Dexterity because, err, strength and constitution doesn't looks hes best stats.
Society*
Occultism*
Intimidation*
Diplomacy*
Thievery*
Stealth*
Arcana
Medicine (get using Skilled Human)
Nature
Performance
Religion
Crafting
Legal Lore
Underworld Lore
* These skills that will be improved every level up to legendary.
1: Natural Skill (ancestry), Streetwise (background), That's Odd (class)
2: Solid Lead (class), Discreet Inquiry (skill)
3: Leverage Connections (lvl 2 feat) (skill), Prescient Planner (general)
4: Lie Detector (class), Quick Contacts (lvl 2 feat) (skill)
5: Unmistakable Lore (skill), Natural Ambition (ancestry) [Underworld Investigator]
6: Connect the Dots (class), Assurance (Society) (skill)
7: Biographical Eye (skill), Expeditious Search (general)
8: Whodunnit? (class), Fabricated Connections (skill)
9: Read Shibboleths (skill), Cooperative Soul (ancestry)
10: Just One More Thing (Objection!/Hold It!) (class), Shameless Request (skill)
11: Automatic Knowledge (Society), Incredible Scout (general)
12: Reason Rapidly (Empiricism)/Make 'em Sweat (Interrogation) (class), Hobnobber (skill)
13: Stubborn Persistence (ancestry), Confabulator (skill)
14: Clue Them All In (lvl 8 feat) (class), Eyes of the City (skill)
15: Reveal Machinations (skill), Incredible Initiative (general)
16: Reconstruct The Scene (class), Legendary Negotiation (skill)
17: Legendary Thief(skill), Heroic Presence (ancestry)
18: Lead Investigator (class), Underground Network (skill)
19: Glean Contents (skill), Canny Acumen (Fortitude)
20: Just the Facts (class), True Perception (skill)
Obs.: These feats meets the level requirements but aren't exactly in the correct optimized order.

dirkdragonslayer |

I know this sounds dumb, but I feel like he would be a Gnome for Gnome Obsession. So he would only need 1 day of downtime (investigation day) to become an expert on a case's lore quickly with Additional Lore scaling. Eclectic Obsession let's you have your "Hold It!" moment as you suddenly find a super specific lore to focus on in the moment. Wait did you say steel samurai... I KNOW ABOUT STEEL SAMURAI LORE.