Some time ago I've created a not-so-awersome version of the lord of blades, an eberron NPC.
It was something focused on construct-lock and TWF, hight crit weapons and so on.
The BSF in my party, a warforged figther 20, challanged him on a 1 to 1 fight, losing his over 350hp in 3 rounds or less, i can't remember.
was something like this
fighter 8 / artificer 5 / warforged juggernaut 5
01 adamantine body, ACF warforged fighter (+3 initiative, +3 vs fear)
02 Construct Lock (ACF warforged fighter, warforged feat)
03 Twf
04 ACF warforged fighter (+2 damage w/t slam or attached weapons)
05
06 ITwf, exotic weapon, double scimitar (B)
07
08 improved critical (B)
09 power attack, ACF warforged artificer (infuse self)
10 Brew Potion (B)
11 Craft Wondrous Item (B)
12 improved bull rush, extend spell (B)
13 Craft Magic Arms and Armor (B)
14
15 persistant spell
16
17
18 craft construscts
persisted wraightstrike, persisted divine power, persisted haste, something else
Tons of immunity in a full metal body.
however u can trade fighter and juggernaut levels for ranger and scout levels: skrimish get critical, immobilize target, coup de grace w/t skrimish damage.