Thought I should elaborate on the relationship between "Sheath and Knife" and "Robin Hood's Death":

Compare Robin`s instructions to Little John in version B of the death ballad (Child 120):

>>>And a broad arrow, I`ll let flee;
And where this arrow is taken up,
There shall my grave digged be.
`Lay me a green sod under my head,
And another at my feet;<<<

... with the sister`s instructions to her brother in the A version of "Sheath and Knife" (Child 16):

>>>`Now when that ye hear me gie a loud cry,
Shoot frae thy bow an arrow and there let me lye.
`And when that ye see I am lying dead,
Then ye`ll put me in a grave, wi a turf at my head.<<<

The main difference here seems to be that in "Sheath & Knife", shooting the arrow not only determines where the gravesite shall be, it is also the means of death. At least, the apparent meaning is that the brother is to shoot his sister when she calls out and bury her where she falls. Another possible interpretation of the ambiguous text, however, is that the sister is in labour [she is said earlier in the A version of the ballad to be "wi child"] and knows she is dying, and that she is requesting the brother to shoot an arrow at the moment she gives birth (i.e. her "loud cry") simply to choose where her gravesite shall be, not to hit & kill her.

Also note, that in the 19th century version of Robin's Death, Robin gives his burial instructions not to Little John, but to the Abbess, who described repeatedly as his sister (although she is his cousin and his murderer in the original ballad):

Of Robin Hood's Death and Burial - Sebastian Evans (1865)

Cheers, Hester