An interesting point?

Question

I'm a length of hard wood
Hooped with iron at each end
Used for making a block
Or a case to defend

My sound is like silence:
Dumb, irrelevant am I
Talk about me forever
For I point to the sky

Hint 1

I am a single, four-letter word.

Hint 2

The first clue is archaic.

Hint 3

The title is a clue.

Hint 4

But for the difference in sound between a cat's and a cow's, the "sound" clue is homophonic.

Answer 1

moot. Means "irrelevant", sounds like "mute".

Answer 2

I believe it's an

Idea

• It's a four letter word that matches the title (an interesting point).
• It can be used to block other ones or give you something to defend.
• Its sound is quiet (especially while forming one)
• Dumb ones are useless/irrelevant
• They're constantly talked about
• Point to the sky... Either the "light bulb" effect or something pithy about it "taking flight"

I can't figure out the wood/iron clue, but I assume I'm missing something obscure, since the hint specifically calls it archaic.