Ah, it's σύνοιδα :). So a translation would be:
"I enjoyed being praised. For if our son Evagrius is famous, the fame is ours; for the virtue of the children is the glory of the fathers. But we, in words, know little or nothing usefull at all about ourselves as your son, for there is nothing great among words for us; but one is for him instead of all and the greatest: we contributed together, I will not deny, to the fear of God and the keeping in mind of the faith in those that are near."

Sounds a bit confusing though.

It is confusing, because you keep hurrying, while you need to think more. At www.ellopos.net/elpenor/lessons/lesson2.asp">Elpenor's second Greek lesson I suggest to treat a difficult sentence like a puzzle.

"know little or nothing usefull at all about ourselves": you missed the accord of ἡμῖν αὐτοῖς ὠφελήσασι, although it is in a series.

but one is for him, etc: bring it to a normal order (already existing in the original).

to the fear of God: why "to"?

I don't get it :(

Yet us, as regards words, [σύνισμεν ἡμῖν αὐτοῖς ὠφελήσασι τὸν σὸν υἱόν:] we know ourselves to have offered nothing or perhaps little to your son, since for us words is not something great.

But we brought him instead of all just one and the greatest, which I won't deny, fear of God and the persuasion to despise the present life.

Thank you very much! From your translations, I took the following conclusions:
- ὠφελήσασι is the dative of the aorist participle for the verb ὠφελέω;
- in τὸ τῶν λόγων, τὸ is instead of quotes: like he would have said: "words";

Is this right? And was the rest of my translation ok?

Thank you again :)

Marian