I'm pretty sure people have published lists of iOS fonts, if there are no likely culprits on these lists, iOS ships Arial Unicode so there's a chance it came from there. Alternately you could ask Apple. :-)

Si

I see no obvious culprit in this list http://iosfonts.com/.

Given that on Mac OS X the only Armenian-capable preinstalled fonts are Michael Everson’s Mshtakan and Arial Unicode, I think Simon is right.
But, since Arial Unicode only comes in Regular, it would be interesting to know how italics and bolds are rendered.

I haven't looked at Arial-Unicode's Armenian for a while, but
it was unusable; this one isn't, so I think it's something else.

hhp

There could be a hidden font (but, usually, this kind of fonts too come only in regular. Heck, even Lucida Grande still lacks italic!).
Anyway, for comparison, here’s non-mobile Safari Armenian rendering:

When I want to know what font is used to render some text, I copy it and paste it in TextEdit. That seems to give reliable information. Here is what I get:

On the other hand, if I paste the very same text in Pages (on OS X 10.5), the look remains the same, but Pages tells me the font is Helvetica. I thus guess that Pages on the iPad would not be more useful to learn the font.

There is only one font in iOS that provides Armenian glyphs. It's called .PhoneFallback:

The description reads:

»The .PhoneFallback font is used by the operating system to display Unicode data when the font requested does not have the capability to handle the requested Unicode. PhoneFallback is based upon the Open Source font Bitstream Vera and the public domain font Deja Vu. Bitstream Vera is a trademark of Bitstream, Inc., designed by Jim Lyles. See complete license details at http://dejavu-fonts.org/wiki/index.php?title=License«

Indeed the Armenian in .PhoneFallback is identical to that in DejaVu Sans.

Great snooping Jens! Thanks.

hhp