I was comparing some Greek agent nouns, and it's appearing a clear pattern, with eu-suffix after o-grade agent nouns, in the formula verb *CeC-, noun *CoC-os = noun *CoC-eus, as can be seen below:
phero: - phoros - phoreus
theino: - phonos - phoneus
speiro: - sporos - sporeus
gignomai - gonos - goneus
temno: - tomos - tomeus
trepho: - trophos - tropheus
There's a lot of discussion about eu-suffixed word as IE or non-IE origin? What's the current view? Is it
possible that the suffixation gradually became useful to prevent IE alternation e/o?
JS Lopes