Is unuseful more useful than useless?

I was wondering if the word unuseful is different from useless. I want to use the former to mean "not very useful", and be less offensive sometimes than to use the latter, which means "of no use at all" IMO.

Dictionaries such as M-W seem to suggest unuseful is the same as useless

: of no practical value : unhelpful, useless (nameless and unuseful plants such as flourish under barrels — Thomas Wolfe)

But does this difference actually exist?

Useless is and has always been the more common term between the two. Unuseful is more literary and was common especially in the 17th century. It was mainly used with a negative connotation:

Useless

• Of things, actions, etc.: Destitute of useful qualities; serving no good end or profitable purpose; not answering or promoting the proposed or desired end; unserviceable, ineffectual, inutile. In frequent use from c 1650.

  • 1593 Shakes. Lucr. 859 The aged man..like still-pining Tantalus..sits, And useless barns the harvest of his wits.

Unuseful

• Unprofitable, useless. (Very common in 17th c.) In 18th and 19th-c. use chiefly with negatives.

  • 1598 Dallington Meth. Trav. V j, Bowling, carding, dicing, and other vnlawful and vnvseful games.

  • 1624 Heywood Gunaik. v. 219 Gold and silver they despise,..esteeming it rather an unusefull burden than a profitable merchandize.

(OED)

Ngram: useless vs unuseful