This last patch has a major boon to the DD output of thf (1-h DDs in general) in that we can now cap attack at the same cRatio of 2-h DDs. THF still operates at a disadvantage though, because we have no native attack boosts for the job. Because we do have DW3 natively though, we can go thf/war for great results. I don't think we will ever be able to match the damage output of a really decked out DD, but since SE is working on fixing enmity, maybe we can go back to being a respectable niche job and our slightly lower DD output will be wanted along with it.
That being said, as far as maximizing your output in the damage category is concerned. You really do need to focus on a lot of gear. We already went over improvements for your Mercy Stroke set. Your TP set definitely needs some focus as well. There are pretty much 3 stages to upgrading THF tp sets right now.
Stage 1: Abyssea
Vlor went over this a little, but the very least to get your thf respectable is all located right in abyssea. You are looking at a 25% haste set, with some multi atk thrown in. Goals for this stage are.....
Range: Raider's Boomerang, Why: 3% DW, very easy to get
Head: Raider's Bonnet +2, Why: 6% Haste 3% TA
Neck: Rancor Collar, Why: 5% crit hit rate, Twilight Torque, Why: 15% damage reduction swing when you don't want extra damage from RC
Body: Raider's Vest +2, Why: 5% Haste
Hands: Raider's Armlets +2, Why: stats
Ring: Epona's, Why: 3% DA 3% TA
Back: Atheling Mantle, Why: 20 atk, 3% DA
Waist: Twilight Belt, Why: 7% haste, 2% DA
Legs: Raider's Culottes +2, Why: 5% Haste
Feet: Raider's Poulaines +2, Why: Not for TP, but +1 TH. there are a lot of options here, I used Homam Gambieras
Why this set, well, 4/5 AF3 +2 gives you ~8% triple TA damage, capped haste with twilight belt and either hands or feet. Lots of DA/TA. Easy to get
Stage 2: NNI (Kind of mostly optional, but gives a lot of great Exenterator gear too).
Pieces to get to upgrade TP.
Body: Thaumas Coat, Why: Um.... are you blind??!! 12 acc, 4% haste, 3% DA/TA/QA all on one piece... sick!
Hands: Thaumuas Gloves, Why: Not absolutely necessary, can go for last haste slot
Legs: Thaumas Kecks, Why: 6% haste, 9 str/agi, 14 acc/atk
Feet: Thaumas Nails, Why: No haste, but good atk, great SA and TA piece about even with AF3+2 hands/Homam feet to swap Thaumas Hands/Feet.
This is where I am at right now. I TP in 4/5 Thaumas + Raider's Bonnet +2 and Twilight belt for 26% haste. I double attack a lot. Much stronger than Stage 1.
Stage 3: Salvage (can skip stage 2 if you have access to this, Except thaumas body probably)
Head: Skadi Visor +1, Why: 7% haste, 4 stp, 10 atk, 13 DEX/AGI. Awesome piece
Body: Skadi Cuirie +1, Why: 7% DW, acc, atk, DEX, AGI. Great piece, opens up options for TP gain
Hands: Skadi Bazubands +1, Why: 4% haste, str, atk
Waist: Patentia Sash, Why: 5% DW, stp, atk
Legs: Skadi Chausses +1, Why: 6% haste (hidden), stp, acc, atk
Feet: Sigyn's Jambeaux, Why: 4% haste
This stage is the awesome stage. There is so much haste available, that your consideration becomes where can I drop haste to add DW. The nice thing about our dual wield options is that all of our DW reductions have stp on them to counteract the TP penalty. (Skadi doesn't actually, but the other gear does.
If stage 2 isn't an option, you should aim for
Skadi +1 Head/Body/Hands/Legs + Sigyn Feet. Swap Twilight Belt out for Patentia Sash. This takes you down to only 21% haste, but you gain 12% DW for it. This set comes with significant stp as well, ~5.4 tp per hit, vs. 4.8 on stage 2
If you have access to stage 2 gear, the absolute best we can get at the moment is
Thaumas Coat + Skadi +1 Head/Hands/Legs + Sigyn Feet + Patentia Sash. 25% Haste, 5% DW (8% with raider's Boomerang), lots of stp