What's your char name in Fel? I solo PvP on Napa too.
And no, that Twinkling Scimitar will not be leeching 5 Mana each hit in PvP, especially if you're fighting someone with all 70's Resists. That Twinkling Scimitar would be doing about 13-15 damage a hit to someone in all 70's Resists, which means you'd be leeching about 2-3 Mana if the Mana Leech goes off. You'd have to hit and leech about 4-5 times to regain enough Mana to do 1 Special. Even an Ornate Axe with high Mana Leech % hitting for 20s damage to someone only leeches about 5 Mana.
That Diamond Mace is better for PvP than the Twinkling Scimitar. With decent Stamina, it will swing at max speed, Stam Leech keeps Stamina up to keep it swinging at max, it hits alot harder, and it has better specials for PvP. A Conc Blow from that Diamond Mace would likely hit harder than an AI, and that's without the Fireball going off.
While you're wasting Mana on trying to get Bladeweave to do a good Special, he would just sit there letting you get low on Mana, then hit you with a Conc Blow and there goes about half your health, more if the Fireball goes off. Conc Blow deals damage based on the difference between the victim's current health and mana. It's also direct damage so it ignores Blood Oath and RPD. I've killed plenty of Necro/Mages with Conc Blow spam after they got too confident and stayed too close to me for too long when they Blood Oathed me.
HLA really doesn't do alot against Samurais, since Lightning Strike gives +50% HCI, which with 15%+ HCI from suit, completely counteracts HLA.
Stam Leech is better than Life Leech or Mana Leech for PvP due to the fact that it leeches back the amount of damage you do. You hit something for 30 damage, you're gonna leech back 30 Stamina. Which is extremely useful considering it saves you the Mana/DCI of casting Divine Fury, and you don't have to carry tons of Total Refresh Pots.
With a good amount of LMC/MR, that Mace would actually be viable in PvM, especially on a Paladin. Paladin's don't need much Mana except for EoO and Con Wep, have enough LMC/MR and by the time your' Con Wep wears off, you would of regenerated all the Mana you used for it back, and can do it again, keeping your Mana stable. I was able to keep my Mana stable the entire time i was fighting a Travesty earlier on my Macer/Paladin with a Diamond Mace that has 46% Stam Leech/26% Harm/6% HCI/20% SSI/39% Dam Inc, i was using EoO and Con Wep, was swinging it at Max Speed (1.25 Secs) after chugging a Greater Agility Pot for +30 DEX.