Hi Sparkle, your interpretation is interesting and I think you nailed it. That knife taking away the corner of the cake (foundation) does indicate some strong reprimand addressed to people or a person who wants to hear nice useless little words instead of the true solid word of God. Well done.
By accepting the true word of God and obedience to that word, crushes us and breaks us but that causes us to be a wonderful fragrance to God ( God is saying that there is the need to be broken before you can be used to your full potential in Christ and produce the fragrance that he is looking for. This strengthens you to be a spiritual house (vessel) in the Kingdom of God. A strong support that can be used to continue building thoroughly and effectively.).