Pretty much every astartes weapon technically requires the user to undergo a series of hefty augmentations (the actual process of becoming an astartes) before they can even hope to use the weapon. But it's a rare astartes who has a bolter built into his face rather than carrying it in his hands.

Which would be a very good place to have a gun once you get past the issue of muzzle flare as it then becomes a literal look and shoot weapon.

Honestly I kind of like the idea of a hyper fast drill weapon being used as a hyper tech analog to a piercing weapon, and not just because of the obvious Gurren Lagan references you can make.

Were I to do this I'd most likely take a previous poster's idea of giving it Fast from The Inquisitor's Handbook, and the ability to ignore armor up to one's agility bonus, and maybe tearing. I'd also be tempted to give it unwieldy or at least unbalanced as it doesn't strike me as an incredibly useful means of blocking a melee attack.

It'd also be an exotic weapon with an availability of very rare at the minimum.

George Labour said:

That's because the Astartes weapons were built for the already Genetically modified and altered Astartes instead of normal humans.

Honestly, I wouldn't give it Fast, but then, as should be pretty obvious, I wouldn't include the weapon in any campaign I run. Unweildy is a good one, as the rotation is going to throw your aim off enough while attacking, bringing it around to parry would be practically impossible.

I can't see using this over a Power Fielded rapier though.

Larkin said:

I totally agree. Of course not all 40K tech is the "best choice". I'm not trying to lobby for this weapon, I just think it's a creative idea & am enjoying going over it in my mind. And with regard to the built-in drill vrs. hand-held version. I for one would prefer a bionic arm without a big drill bit sticking out of it for my day-to-day life. By that logic, why doesn't every soldier in the 40K galaxy have a gun in place of a hand on their bionic limbs? It would probably be easier to install than all those pesky, fiddly fingers!

In the weird dark faery tale setting that is the 40kverse the rule of kewl or just plain exotic often takes precedence over what would appear logical or even incredibly useful.

All it takes is one noble house suddenly deciding that drill swords are a good way to display their superiority to make the weapon become a new subsector (or even sector) wide badge of honor. After a century or eighty then it'll become so entrenched in the typical imperial mindset that anyone saying drillswords aren't all that great will be declared a heretic and be converted into an assembly servitor that makes new drill swords.

Or some minor arm of the ecclesiarchy decides that beleives an ancient text reads as  'piercing the heavens like the drilling sword of the righteous' and thus they need to combine the two tools into one emperor inspired weapon.

Not that I really think such a thing should be a remarkably effective weapon compared to a power sword and other iconics bits of mutilating power, but I see no reason to say it simply cannot be. If anything it'd be a useful means of adding some character to the latest pack of foppush inbred nobles the explorers will be robbing that week.

George Labour said:

Couldn't agree more!

As much as I wanted to give this Tearing, I can't actually think about a solid reason for that. I was thinking high-penetration, Balanced, and Fast. Ultimately, Impact would likely be better than Rending, too.

So, something along the lines of…

Drill Rapier; Melee.
Penetration 4.
1d10+1 Impact.
Special: Balanced, Fast.
Availability: Rare.

And yes; Holy necro, Batman. Holy necro indeed.

In this medieval Warhammer world I created, I designed a bunch of equipment and the Rapier was one of them.  I gave the stats as

Rapier Melee     Class: Melee      Rng:  -       Dam: 1d10R         Pen: 1        Special:  Bal, Primitive        Weight: 2.5     Cost:  50      Avail: Scarce

Stats for other items is listed here.  docs.google.com/document/d/1_5KK1-oyoClSSDXiexVv0Ht_Zz18ZZymwmeCHTUFskE/edit

And yes, I know, I went all out.  The game was interesting but short lived, even though I was about to have the Inquisition arrive and recruit them to serve the "Emperor in the Stars." 

Notice:  The drill Rapier handle/hilt, and the blade, can both be on a rotating swivel, so as to minimize the risk of injury to the wrist.  Though a critical failure could cause the gears to jam thus causing injury to said area.  User discretion is advised. 

 If you want the stats of a rapier just look in the warhammer fantasy corebook and adapt it. My group has been using rapiers for a long time.

See my weapon list here over on the Dark Heresy hombrew board.

Rapier

Damage 1d10-1    Fast, Primitive   Weight 1.75 kg  Availability Scarce

As for this "drill rapier" I say take the chain sword stats, -1 damage, + 2 AP, loss balanced and gain the fast quality, then make it very rare availability.