Breath and Blood: Hands in Spirit and Flesh

(p. 6094)
John’s retcon arm event toward the end of Homestuck is often compared to MS Paint Adventures’ recurring “retrieve arms” gag, but it also forms part of a repeating pattern surrounding John Egbert and the concept of ghostly hands.

Page 6 is an oft-talked about example of this phenomenon, largely because it doesn’t seem to really have any place in the rest of the story. Despite frequent claims that the fourth wall is being broken, the “YOU as READER” character essentially does not interact with the story ever again after this.
Notice the cyan-and-blue colour scheme the cake takes on while being carried by the “reader’s” hand.

You make a LEFT HANDED REMOTE GHOST GAUNTLET to complete the pair.
An uncannily similar concept crops up over a thousand pages later with the ghost gauntlets, which John alchemises from slime left over by Nannasprite. This explains their colour scheme, but it’s important still to take note of the similarities to John’s iconic god tier colour scheme that appears a whole lot later, as well as to the colour scheme of the cake picked up back on page 6.
Also take note of this line used to describe the ghost gauntlets’ power:
The GHOST GAUNTLET appears to have a considerably higher lift capacity than your own puny arms.
This is because all of these ‘ghostly arms’ around John are actually manifestations of his powers as a Hero of Breath, if not literally - though we know alchemised items often do literally channel a player’s internal powers - then symbolically.
The Breath aspect is one of freedom and separation from that which binds. In the heavily Gnostic context of Homestuck, this especially relates to the soul breaking free from the chains of the flesh. As such, the Breath aspect is one that connects heavily to the spirit. Consider the biblical story in which God breathes live into the clay Adam through his mouth (which also ties into John’s role as the a creator father figure, and the association between ghosts and fatherhood).
When the comic says that the ghostly arms John uses as an extension of his physical form are stronger than his flesh arms, this is a comment on his powers as the Hero of Breath and that his soul will always be stronger than his body.

(p. 2303)
Compare this to the Blood aspect’s association with hands. Jack’s offered “blood pact” with Karkat on page 2303 is often considered a precursor to the Blood symbol, and importantly takes place in the joining of two hands. The Blood aspect is not concerned with separating the spirit hand from the hand of flesh, but rather by making the flesh stronger through bonds.
Take note of another phenomenon that frequently befalls Jack Noir; almost every iteration of him loses one of his physical arms. This is another occurrence often connected to the “retrieve arms” gag, but we can also contrast it with the ghostly “removal” of one of John’s arms.
Vriska’s connection to this phenomenon could be read in two ways. It acts as a symbol of her connection to the Blood aspect when she antagonises Tavros, a Hero of Breath; but it also connects her with a “blood fued” shared with her “blood” ancestor Mindfang as well as Jack Noir himself.