So recently put together a Kat/Inv, the goal was simple, I wanted a Scrapper that could Tank the ITF, I wanted to be able to use "Call of the Wolf" and never invite a Tank on the ITF again.
Still leveling it, but so far it seems to be very impressive.
Below is the build I'm aiming for, but for your questions -
Tough/Weave? YES! - It will send your smash/lethal survivability through the roof, I'd strongly recommend you pick up Kinetic Combat IOs to further help it. Seriously do it right and you will be stronger than a Granite tank,
Positional Defense isn't hugely nescessary, Tough Hide, Weave and CJ will give you strong enough melee defense that double stacking DA will softcap you to melee anyway.
But positional isn't the one you should aim for, it's the S/L, again I recommend Kinetic Combats here.
As for Skippables? not much I'm afraid, you can skip Unstoppable in /Inv, and as for Kat it depends what you're aiming for, a solo build could skip the AoEs for examples but . . . .
Anyway, below is the build I'm aiming for,
Hero Plan by Mids' Hero Designer 1.401
http://www.cohplanner.com/
Click this DataLink to open the build!
Steel: Level 50 Magic Scrapper
Primary Power Set: Katana
Secondary Power Set: Invulnerability
Power Pool: Fitness
Power Pool: Leaping
Power Pool: Fighting
Hero Profile:
Level 1: Gambler's Cut -- (A)(3)(3)(5)(5)(7)
Level 1: Resist Physical Damage -- (A)(9)
Level 2: Flashing Steel -- (A)(37)(39)(40)(40)(40)
Level 4: Temp Invulnerability -- (A)(7)(9)
Level 6: Build Up -- (A)(34)(36)(36)(37)(37)
Level 8: Dull Pain -- (A)(15)(17)(17)(31)(46)
Level 10: Divine Avalanche -- (A)(11)(11)(13)(13)(15)
Level 12: Swift -- (A)
Level 14: Health -- (A)(43)(45)(45)
Level 16: Unyielding -- (A)(46)(46)
Level 18: The Lotus Drops -- (A)(19)(19)(21)(21)(23)
Level 20: Combat Jumping -- (A)(23)(25)(25)
Level 22: Stamina -- (A)(42)(43)(43)
Level 24: Boxing -- (A)
Level 26: Soaring Dragon -- (A)(27)(27)(29)(29)(31)
Level 28: Invincibility -- (A)(31)
Level 30: Super Jump -- (A)(50)(50)
Level 32: Golden Dragonfly -- (A)(33)(33)(33)(34)(34)
Level 35: Tough Hide -- (A)(36)
Level 38: Tough -- (A)(39)(39)
Level 41: Weave -- (A)(42)(42)
Level 44: Resist Elements -- (A)(45)
Level 47: Calling the Wolf -- (A)(48)(48)(48)
Level 49: Resist Energies -- (A)(50)
------------
Level 1: Brawl -- (A)
Level 1: Sprint -- (A)
Level 2: Rest -- (A)
Level 1: Critical Hit
Ooo I wonder how I ever managed to not notice this post.
First things first; answers to your questions.
Tough/Weave? When levelling up I'd take Tough, but not Weave. It'll cost you too much Endurance unless you have set bonuses with +Recovery or +End.
Defenses? Go with Invuln's typed.
Skippables? Calling the Wolf, Unstoppable and maybe Flashing Steel. Of the two exotic resistance passives, Resist Elements is the more skippable.
Check my guide for further info 
- @DSorrow - alts on Union and Freedom mostly -
Currently playing as Castigation on Freedom
My Katana/Inv Guide
Anyone who doesn't take truth seriously in small matters cannot be trusted in large ones either. -Einstein
So I've decided to give up on Broadsword entirely and reroll as a Katana/Invul because Katana is sweet.
So, the inevitable questions:
Tough/Weave? Y/N? Stupid question that my squishy mentality is forcing me to keep asking even though I should know better?
Do I try for positional defense (ranged and AoE to go with Divine Avalanche) or roll with Invul's typed defense?
Which are the skipabliest of the skipables?
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