# Who is like you, a people saved by Yahweh ... majesty?

"There is no other people group like you, a people whom Yahweh has saved ... majesty." 

# the shield of your help

"the one who protects you and helps you" 

# the sword of your majesty

"the one who enables you to win battles and so have majesty" 

# you will trample down their high places

Possible meanings are 1) the Israelites will destroy the places where the other people worship false gods or 2) the Israelites will walk on the backs of their enemies when the Israelites defeat them.