So I think in the case of the oni/samurai, it'd be useful to cite the fluff:
Two legs are not better than four when talking
drone design. The Nissan Shogun first took the
niche fame of the Ares Duelist and made a design
far superior, though still limited by its metahuman-
like frame, but the Samurai and Oni blended
metahuman with…well, something else.
This establishes that the basic frame is bipedal and "generally" anthropomorphic in layout, but the last few words say that it is still obviously different in some other way or ways.
The Samurai
falls in the medium-size category, while the
Oni is large. Both are specifically outfitted when
ordered from Nissan with a quartet of retractable
blades on the arms and heels, and each arm has
a standard weapon mount.
This says:
1) The Samurai is medium sized, and the Oni is large sized.
2) Each of the four limbs comes with a free blade "mounted" therein.
3) those blades are "retractable"
4) (implicitly) 2 of the 4 limbs are deemed to be arms, and (explicitly) these limbs have additional standard weapon mounts.
Each of the Samurai’s
arms can fit something SMG size or smaller with
fifty rounds of ammo; the Oni can hold a rifle and
one hundred rounds in each arm.
Limitations on the size of the weapons you can put in those free, arm-located weapon mounts.
The big design
advantage comes in terms of speed, but it sacrifices
some combat ability.
Descriptive fluff with no hard crunch.
These designs can bend for
four-limbed movement but lose access to all weapons
while doing so.
This calls back to the very first passage, which said that the drones are anthropomorphic, yet retain decidedly inhuman appearance. Explicitly, this is a body plan that's not just capable of, but desinged for, dropping down to 4 limbed movement. This has implications on the comparative sizes and lengths of the arms and the not-arms (presumably: not-arms are legs).
Tangent: this is an explicit ability, but it's unclear what mechanical benefit you GET for losing access to your weapons. GM prerogative, I guess. Presumably its speed goes up and/or handling goes down. And/or bonus edge on piloting tests. so on.
So... back to your followup questions:
Thank you for your detailed feedback.
A few more question:
B1) Does that mean that...
- If an Oni/Samurai uses a weapon mounted to a weapon mounts in the arm, the jumped-in rigger uses "Engineering / Gunnery"? (as the weapon is mounted to the chassis)
I would say yes. It sounds like these drones are like mini-mecha. No indication that the drones even have hands... the weapons in the arms are explicitly weapon mounts.
- If an Oni/Samurai uses a firearm, which it holds in its hand, the jumped-in rigger uses "Firearms"?
- If an Oni/Samurai uses a blade, which it holds in its hand, the jumped-in rigger uses "Close Combat / Blades"?
Non-sequitur in both cases, as there are no hands for wielding non-mounted weapons.
However.
That's not an official ruling, and it's certainly possible that a GM might say that they DO have hands (that turn into feet when it goes down on all fours). If your GM is going to say yes they have articulated hands: then yes, the jumped-in rigger would use whatever skill he'd use while using that weapon in his own natural hands.
- If an Oni/Samurai uses its build-in-blade, the jumped-in rigger uses "Engineering / Gunnery" (as the weapon is mounted to the chassis) or would it use "close combat / blades" as for cyberspurs?
I would say none of the above. I'd say a jumped-in rigger using a blade mounted on the chassis/limb would make a piloting test, with an AR as derived from the #6 basic on pg 196 and an arbitrary DV 3. Not derived from anything- there's just no such weapon as "retractable blade) and DV3 seems like a decent WAG... based on the range of established knives coupled with the factor of the drone menacing a target with a strike from no fewer than 4 potential directions.
B2) According to the fluff text, the Oni/Samurai does NOT have a hand, thus could only really hold a firearm, if a weapon mount is replaced by a cyberhand, which probably is a topic for the upcoming Rigger book? As of now the Oni/Samurai seem to be the only anthropomorphic drones in SR6.
There's no allowance for cyberlimbs on drones in the CRB. However there were such rules though in the previous edition's Rigger book... so maybe there will be again this time around as well.
C) Regarding martial arts, that also probably would only be possible if the rigger uses "close combat" skill, thus only if a cyberlimb has been added to the drone? (or the build-in-blade counts as cyberspur, see B1)
As I opined, I'd think it's more of a case by case basis... where the crucial factors are the specific combination of the art/technique and the drone. For example, how could you do an arm bar while Jumped into an R2-D2 drone? The number of possible interactions coupled with the lack of knowledge of what most drones specifically look like would mean this has to remain GM fiat rather than trying to codify.