Wishes...
Get rid of ALL Pseudo-Feats. Give the PCs the REAL Feats, instead!
Ambidexterity gives full Strength bonus to both hands. Adding Two-Weapon Fighting gives -0/-0.
"Swashes" (a contraction of "sweeping smashes"), known as bashes in 3e, can be conducted with bucklers (hence the word "swashbucklers").
Remove the restriction that bucklers can't be spiked. Not only did they exist historically, but they also existed in 1e (Unearthed Arcana).
Give Elves back their bonus to INT, explain trancing (are they aware?), give them back +1 with all swords and bows, explain why a chaotic race prefers Wizardry to Sorcery, give them back their 1e ability to cast in armor (which other races couldn't), give them back their 90% resistance to Sleep & Charm. (This won't happen, for backwards compatibility).
FIX THE PSION AND RANGER! The Psion is the weakest class, and the Ranger the next-most. How to fix them and still be backwards-compatible is the problem... For the Ranger, some bonus Feats and special abilities should do the job. The Feats would replace Ambidexterity/T-WF, and the extra ability might give bonuses to all movement skills: Balance, Climb, Hide, Jump, Move Silently, Profession (Guide & Sailor), Ride, Swim, Tumble, and Wilderness Lore. Perhaps Ranger level/2, rounded down?
Rework spell levels totally (won't be done).
Remove the restriction that Spellcraft checks to recognize spells require listening to the WHOLE spell! Since all spells are spoken in Draconic, and the words are the same for the same spell each time, it makes no sense, and it makes no sense that you can counterspell if you have to listen to the WHOLE spell (meaning it is already cast) before you can begin doing anything to counter it!
Fer cryin' out loud, return invisibility to a simple penalty to hit... It used to be -4, but that's too low, now. The current system is just too many rolls for too little! First you roll to hit... then you roll for a miss chance... then I re-roll to hit for my Blind-Fighting... It used to be that I rolled once, with -4 to hit, and Blind-Fight decreased that to -2. Simple. Easy. Better!
While we're at it, the rules for invisibility invalidate my skills, elevating magic WAY over them! I can't attack an invisible creature AT ALL, unless it attacks me, I have Blind-Fight (and it is within 30'), I have magic, or I exceed its Move Silently with my Listen by 20 OR MORE, or make a DC 20+ Spot? How can I succeed in a Listen and know something invisible is out there, and NOT know where it is, at least well enough to target it with a missile weapon?
(Consider this: A Ranger with Spot & Listen maxed out, Blind-Fight, and a bow, up against a flying goblin sorcerer with improved invisibility... No Spot, cause there's nothing to spot. He's seventh level, so CAN'T POSSIBLY succeed in a DC 40 check. The Gobbie is outside 30', so Blind-Fight is no good! Gobbo can lob fireballs and magic missiles, and all the Ranger can do is Ready an action to fire when it appears, or blindly pick a square and fire into it to see if the dumb thing is there!)