In my response about norse in norse, I cited the proto-norse word
strong in the masculine and weak in the feminine. Instead of just
wasting a post on clarifying the situation, I will try to be more
constructive by showing a few norse examples together with their
early proto-norse equivalants. Proto-norse is the language which
'explains' old norse - for this reason, most of you will probably
find these examples interesting. They are early proto-norse, which
means that they are from about 100-200 AD :)

strong masculine:

*norþrônijaR - norroenn
*norþrônijanô - norroenan
*norþrônijummu - norroenum
*norþrônijas - norroens

strong feminine:

*norþrôniju - norroen
*norþrônijô - norroena
*norþrônijêRê - norroenni
*norþrônijêRôR - norroennar

The name of the tongue is a weak feminine: norþrônijô, norþrônijôn

Some basic sentences:

Gôdanô daga. - góðan dag
*ek em mannaR norþrônijaR - Ek em maðr norroenn.
*is þû kwenô norþrôniju? - Ert þú kona norroen?
*þat ist norþrônijatô barna - Þat er norroent barn.

The syntax is fairly free, so you can also place the verb at the end
of the sentence for a more 'archaic' effect:

*sâ karilaR norþrônijaR ist - Sá karl er norroenn.
*hundaR hinaR fram harudalandê ist - Þessi hundr er frá Hörðalandi.
*ek fagranô kattu aih - Ek á fagran kött.

A little fancier:

*In daga tîwas dagaR ist andi ana morgana wôdanas dagaR.
- Í dag er Týsdagr en á morgun Óðinsdagr.

Regards,
Konrad