1)
What is "[Armenos] ha'Keri'os"?
1.
Rashi: It is the name of a place, like "v'Al Keri'os v'Al Batzrah" (Yirmeyah 48:24).
2.
Radak (2-3): It is the name of a city in Mo'av, its capitol.
3.
Malbim: They are fortified cities in Mo'av.
2)
What is the meaning of "u'Mes b'Sha'on Mo'av bi'Sru'ah "?
1.
Rashi: [He will die] in the clamor of the war of Mo'av.
2.
Malbim: He will not fight at all ? "Eich Hifnah Oref Mo'av Bush v'Hayah Mo'av li'Schok veli'Mchitah l'Chol Sevivav" (Yirmeyah 48:39). When he hears the clamor of war and Teru'ah, he will die from great fear, from the sound of the Shofar.