What Brachah did he give to David?
Radak (Shmuel II, 8:10) #1: He should succeed in his wars.
Radak #2 (Shmuel II, 8:10): It was a gift, like it says "uv'Yado Hayu Klei Chesef..." We find that a gift is called Brachah - "Kach Na Es Birchasi Asher Huvas Lach" (Bereishis 33:11).
Malbim (Shmuel II, 8:10): He should have an influence of strength to crush his enemies.
What is the meaning of "Ish Milchamos To'u"?
'Rashi': He was his adversary 1 . This is proven above - why did David fight Hadad'ezer is Chamas?! Rather, Hadad'ezer went to Chamas to fight To'u, and while he was there, David fought him. (Hadad'ezer).
Malbim (Shmuel II, 8:10): To'u joined David with love, for they had a common enemy.
Why does the verse teach about the Kelim of gold, silver and copper?
Vilna Gaon: He sent his son to David with these Kelim.
