1.5/5 stars. Rounded down. I am unconvinced this one works, but I like the concept.
Background.
These assassins are the tradition blade masters of the clades. They are sword masters supreme and have a bit of martial regality about them if I'm reading the background correctly.
Strengths.
The ranged weapon is great! The needlespine blaster can pump out a deadly array of shots which will certainly destroy things.
The blade itself is okay overall - a bit like a power sword with rending.
Weaknesses.
I think I have a fundamental problem with the special rules. On the one hand, the Death's Artisan special rule must always issue a challenge - this is okay in principle. They can then stat match WS and I to their opponent. This is also fine, but honestly, they're going to die quickly with a save of 4+. They're too squishy for this kind of thing. Much better that they are not issuing challenges at all and just killing things.
Then there's the odd interaction with decapitation strike. You can forgo your usual attacks for a single AP 1 attack with murderous strike at 2+. This is great. But if you're matching the WS, it only has a 50/50 chance of even hitting. It is a massive gamble. But its also one you're going to probably have to take given you have AP3 with your sword otherwise and you're squishy. But the strike is also unwieldy, so you're probably dead anyway if anything else is striking at initiative with (e.g.) lightning claws, or Emperor's Children in general.
Hence overall, despite being a swordsman, you're actually better off being a very close range pistol wielder. And if you try to be a swordsman, you're probably going to be wiped away quickly, unless you face a softer target or one that goes as slowly as you do? But then the enemy will have more attacks in all probability. Wiped out either way. Grim.
Builds.
There are no builds available to discuss here. I don't regard this assassin as playable overall. Apologies.