The Dishwasher Dead Samurai

you unlock the Chainsaw later in the game after you beat a certain boss. (you have to finish the level to keep the Chainsaw)

You can replay levels (with the guns you find later in the game)

Dont use the sword to travel either, just wall run when you need to

after you get chainsaw,reload lvl St. Crux Cemetery , push on D-pad to right to select chainsaw, then go through the lvl. At first hole you must go down to get the Key. Then go to right. when you will come to big vertical wall,change the weapon to sickle's and with them you not get trouble to run up the wall. But be carefull there are many enemy's. Quick push LB to use magic, and fast push d-pad to right to change weapons to chainsaw again (RB botton to change from the sword).
Then it's easy to finish the lvl.
P.S. sorry for my bad eng ^^

--------Credit to xbox360achievements.org---------

In order to do this achievement, you'll need to find the chainsaw, which you won't do the first time through St. Crux, so don't even worry about it. The chainsaw is found half way through the "L'Opera Dramatique" level later in the game after beating the pumpkinhead boss. After you've killed him, finish the level (to save the item to your inventory) and head back to St. Crux. Equip the chainsaw, run through the level with it and the achievement will unlock.