This particle, when it follows a noun or pronoun denotes a reflexive. In the sentence
il Ã±amma anÅ«ri nÄ Ä mÅ«rÄna masÄ«rien
il Ã±amma jalÅ«ra rÄ sÄen ÄÃ± nÅ Ä marÄona;
ÄÃ± modifies the 3rd person singular pronoun sÄen to mean “himself/herself”. nÅ means “to, along”. The second clause of the sentence thus means “the wanderer made/held/kept the cloak to him/herself”.
The sentence can now be fully translated:
Happening at the same time:
the North Wind is making lots of wind,
the wanderer is causing the cloak to be to him/herself.
“The north wind made much blowing and the wanderer held the cloak to himself.”