As it is, I cannot guarantee that the header is exact.
As it is, the following text appears to have been based upon
several manuscript variants written in Sweden around the year
1500, which is most likely a kind of estimate, or average value.
The introductory text is a bit long-winded, and I wasn't able
to draw a quick and definite conclusion as to the exact age
of the text. Perhaps, if I put some more effort in it, I will
be able to give more exact dates. But for the time being I think
"1500" will do as indicator.

The text is from a book edited by the well known Swedish scholar
H Y L T É N - C A V A L L I U S , which book was published at
Stockholm between 1850 and 1854. The book's title is "Sagan om
Didrik af Bern".

Here just a small sample, picked at random, just to give an
initial taste:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<pagina 169>
....................Kap. 222.

1 Om konung Aktilius' vänskap med konung Ermentrik.

2 Koning Atilia war en riker konung . han haffde my-
3 kin winskap mz ermentrik . koning / han satte sin frende
4 till ermentrik konung . som osid het . mz xij riddara .
5 konung Ermentrik fik hanum sin frende igen som
6 walter het aff waldsken han war tha ekke mesta ga-
7 mall . En jomfrw war mz Attilia konung . hon het hil-
8 degulla . jarlens dotter aff greken . hon war tit sat till
9 gisl . walter haffde henna ganzke ka'r.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Note in line 2 the adjective "riker". It has the -er ending,
which I read as the regular singular masculin nominative, here
used in the same fashion as is common in Old Icelandic.
(and in modern Icelandic too). In the modern Scandinavian
languages it has, however, been lost. Also note the various
forms of the personal pronoun "han", "hanum" etc. These too
are older forms that conform to the Old Norse forms.
Apart from these, though, the text has quite a modern
appearance, and to me it is quite easy to read: The language
clearly is already miles away from the difficult Old Norse.

Xigung.