"Upon reaching the end of the Fire Temple, Demon Lord Ghirahim confronts Link for a second time. If you recall the first Ghirahim encounter, you will quickly notice that this time around Ghirahim has cranked things up a notch. He still has two phases, and the easiest way to defeat him is still by utilizing Link’s Shield Bash." - JPS
Really? Spoiler in the title.. They don't have shame now.
And that's why I was a Skyward Sword virgin aka by not checking anything/staying up to date with this game via online websites.