Here is what the Glossa Ordinaria has. By the way I just had the Glossa on 1-3 John translated into English and will be publishing it very soon!
Verse 6. ***This is, etc. ***Because faith alone and confession of the divinity is not sufficient for salvation and for conquering the world, he also adds about his humanity: therefore he pronounces the blood. ***Spirit. ***That is, the human soul which has gone out in the Passion; the water and blood, which flowed from his sides. This would not be possible if he did not have the true nature of flesh. But also before the Passion, his sweat like drops of blood demonstrate the truth of his humanity (flesh). This fact, that the water and blood flows vivaciously from his sides against nature even after his death, was testifying that the body of the Lord after his death is better than living, and his death gives us life. The fact that his sweat flowed as blood in the earth signifies that his blood cleanses the Church throughout the whole world.
Verse 7. ***They are three. ***By this it is apparent that Jesus is the truth, truly God and truly man. And concerning both we have certain testimony. Concerning his divinity the Father, the Son, and the Holy Spirit bear witness. Concerning his humanity, his soul, water, and blood give testimony. The Father has testified to his divinity when he says, “This is my Beloved Son.” The Son himself testifies when he is transfigured on the mount, and he shows both the power of Divinity and the hope of eternal happiness. The Holy Spirit testifies when he rests above Jesus at his baptism in the form of a dove, or when he has filled the heart of those who believe with the calling of the name of Christ.