1)
Why should he put his hand on it?
1.
'Rashi': To strike it.
2.
Ibn Ezra: Can you do so?!
3.
Malbim: Since I gave to you Kel's strength, it suffices to put your hand on it; it will revert to nothingness.
2)
What is the meaning of "Zechor Milchamah Al Tosaf"?
1.
'Rashi': Do not remember your strength more, to make war with it. Tosaf is [adding,] from Yasaf - "v'Lo Yasaf Od Ledatah." There is a Patach under the Samech because it is Sof Pasuk, like "Al Tosar", "va'Tosar".
2.
Ibn Ezra: If you put your hand on it, you will not fight it more, for you will not live.
3.
Malbim: You will not need to fight it in the way of war - one cannot defeat it in war.
