I don’t know if that’s true, but in my experience it is. I had situations where I thought a demon was stalking me after I had repented for mortal sins, so I traced a cross with Holy Water on the frame of my door and above my window and I haven’t committed that sin since.
As to your question on Holy Water, I have a book titled “Why do Catholics do that?” by Kevin Orlin Johnson (a very good read for both Catholics and non-Catholics in my opinion) that has a chapter on Holy Water that states: “…the Lord ordered Moses to prescribe a srrinkler of hyssop for the water and blood used to purify a house infected with leprosy (Lv 14:49-52).” He goes on to say that the Holy Water sprinklers used to have Hyssop in them. Blah,Blah,Blah…Ah, here we go, It says that Solomon had washing basins at the entrances to his temple to cleanse the people physically and spiritually. Then it says how there was a basin at a church in Constantinople that read “Wash not only your hands, but your souls.” That’s a BRIEF history!
Also, if I’ve heard correctly, the Oriental Rites don’t use Holy Water because it’s just more of a Western tradition that didn’t develop in Greece, Egypt, and so on.
Hope this helps!