1)
Why does it say Milchemes? It is not Samuch (the first word of a compound noun)!
1.
Radak: This is known [which Milchamah, so it has the form of Samuch, even though there is no noun after it].
2.
Malbim: Milchemes is the same whether or not it is Samuch. 1
1
I.e. in addition to the word Milchamah, there is a word Milchemes, even when it is not Samuch, just like we find the words Atarah and Ateres. (Heard from R. Yakov Blinde Shlita.)
2)
How were a sword and spear found for Sha'ul and Yonason?
1.
Rashi: This was a miracle. Radak citing a Midrash - an angel brought them to them.
