Valiant golems can be killed very easily. I suggest adding Golem Armor, basically horse armor but for golems. These items would be craftable with their respective materials.

You can already get golems with armor by using terracotta or obsidian golems; the amount of armor they get is configurable.

That's intended to prevent golems from being too strong; as I said, though, you can configure the mod to give them as much armor as you want.

The armor given by those types isn't very high, though.