Feel free to post the tip in the trophy guide if you want to; I've loaned the game out and probably won't be able to get it back for a week or two in order to test your method out (I don't want to absorb it into the guide without being sure it works) - so go ahead and post it, and if it works once I get a chance to test it I'll update the guide and credit you for it.
I do want to add a tip for people having a hard time at the chapter 4 mission 6 boss on nightmare. The two handed axe full square combo stuns him and hits enemies that would aim to attack you. I was having a hard time on phase two for it because I couldn't get him stunlocked with other weapons because I messed up the square triangle combos. Fun square with 2h axe worked for me though.