Shanks and blackbeard clearly even before this chapter paralleled roger and whitebeard. This chapter making it even more clear
We know blackbeard also is connected to xebec in some way with him naming his shop after him + making his base pirate island
If the darkness fruit really was his on top of that itd be even more in out faces. Blackbeard taking the devil fruit powers of both whitebeard and xebec
If shanks really does end up being xebec's son he might have learned or inherited one of his powers. Maybe his sword, some special haki, or weapon of some short.
For someone like xebec who was the captain of whitebeard, big mom, kaido, and shiki + seemingly fought roger and garp in a 1v2 he was definitely more than just his devil fruit power
It'd be cool if similar to how roger likley wanted shanks to surpass him xebec wanted the same thing from shanks. Roger maybe giving his hat up to represent that
So while blackbeard forces his way to inherit their powers and legacy
Shanks was ment to inherit their legacy's but either didn't want to of failed