I am a student at the University of Stuttgart, Germany and I have a 1 year national visa for Germany and now as my holidays are ahead I was looking if my German visa is sufficient to travel to Ireland for some 10 days. I am a citizen of Republic of Armenia.
Summary: Your German visa is not enough, you need an Irish short-stay visa.
Ireland is not part of the Schengen area, so a German national visa is not enough to enter the country. Since Armenia is on the list of “countries whose nationals are visa required”, you do generally need an Irish visa to go to Ireland on holidays.
There is however an exemption for holders of student visas from other EU/EEA countries, which could cover you. But that's only when going to Ireland “as part of a group school excursion” so it probably does not apply to the trip you are currently planning.