The Super Heavy Detachment, which consists of 3-5 LoW units, does get detachment abilities. A single LoW in a Super Heavy Auxiliary Detachment, however, does not. This means a single Wraithknight can't get Craftworld attributes, unfortunately.
pg. 246 of main rulebook:
Every Codex lists a set of abilities that units in a
Detachment gain if every unit in that Detachment is
from a specified Faction. Units in Auxiliary Support
Detachments, Super-heavy Auxiliary Detachments
and Fortification Network Detachments never gain
any Detachment abilities, even if every unit in that
Detachment is from the Faction specified.