Etymology

Formed within English on skyl (n.) + -ful suffix.

PGmc Ancestor

*skeli-

Proposed ON Etymon (OIcel representative)

skil (pl.) ‘distinction, discernment (etc.)’
(ONP skil (sb.))

Other Scandinavian Reflexes

Far skil, Icel skil, Norw skil, Dan skel, Dan dial skil, OSw skil, Sw skäl

OE Cognate

Late -scylian (v.) (āscylian, āscilian, tōscylian ‘to divide’)

Phonological and morphological markers

absence of palatalization of */sk/

Summary category

A1a

Attestation

Common and widespread from the 14c. onwards, incl. Chaucer.

Occurrences in the Gersum Corpus

Cl 1148; Erk 278; WA 645

On the usage in Erk, see Peterson 278n.  The WA occurrence has an adverbial function in context.

Bibliography

MED skilful (adj.) , OED skilful (adj. and adv.) , HTOED ; see further skyl (n.).