Searles wrote from John Koch's slide: 
>"§5. the common Palaeohispanic name Arquius and the regional survival of
>archery from the Beaker Copper Age

>‘The name Arquius probably meant one who had to do with a bow, that is to
>say, an archer, and was derived from a Celtic word cognate with Latin
>arquus and arcus, a bow or arch’ (1891–4, 106). ‘We have probably a trace
>of the word [for bow] in Welsh arffed, “the lap or abdomen”, cf. German
>Schambug’ (Ib., FN 7)."

>The original words seem to have been lost along with the reporting of bows
>and arrows being used in the heroic tales.
This last statement is simply false - of all weapons probably the bow & arrow are the most featured in stories.

I have been looking for evidence of this word 'arcus' being used in mythology.  There really is loads and loads archery and archers in all the stories of all western cultures, so if it was generally used, I would certainly expect it to show up.  

In the insular Celtic stories, I have only found one possible name, which is Arca Dubh lasgair, who is the killer of Finn's father, but I don't know how he did that.  So no idea if its related to 'arcus'. 

But, when I go south, bingo.  Arcas was a famous hunter/archer, the son of Zeus and Callisto whom Hera had turned into a bear.  Arcas nearly accidentally shot his mother in bear form with his bow and arrow, and the two were then put into the sky as Ursa Major and Minor.   Arcas is also confused at times with Bootes and its bright star Arcturus (bear-watcher), and there certainly is evidence that 'art' and 'arc' are often confused and morph between each other.  

But here's something someone might have an opinion about?   Without a doubt the most famous archer from the oldest story around is Hercules.  He is commonly seen using his bow in the stories, and without his bow the siege of Troy could not be won.  In the traditional constellation representation he is seen as the kneeling archer with his bow and his club.    But, interestingly in early Greece this constellation was not known as Herakles at all, merely a kneeling warrior.   Despite this, somehow Herakles is said to somehow find its way from Greece to the Etruscans to the Roman Hercules.    Here I suspect we are labouring under the old paradigm that everything comes via Greece, rather than a story that may have originated in Etruscan and perhaps through to John Koch's region in the SW.
Wikipedia: 
The Latin name Hercules was borrowed through Etruscan, where it is represented variously as Heracle, Hercle, and other forms. Hercules was a favorite subject for Etruscan art, and appears often on bronze mirrors. The Etruscan form Herceler derives from the Greek Heracles via syncope
< NW IE *haérku̯os  ‘bow and/or arrow’; Latin arcus, earlier arquus; Gothic arƕazna ‘arrow’, OE earh.
So this is my question:  Is this very ancient tale and name of Hercules from this same old root of *haérku̯os  ‘bow and/or arrow’  ?   It's maybe unanswerable in a linguistic sense, given that the story is perhaps many millennia old.  But no harm in asking the question ... ? 

Its funny to find the two names together in one of the inscriptions in JK's list: 
[H]ERCUL[AN]AE ARQ[VI]C(I) F(ILIAE) (HEp, 11, 386 — Salamanca). 

Interesting that he also gives another instance of this confusion between 'art' and 'arc' 
Arcobriga:  probably not ‘the hillfort of the bear’ 

Helen