Iwaku clue: HOW DID THEY DO IT!?

You can do more things with Rope and have more alibis while doing so.

So, Candlestick.
 
Tie up with the rope,

Cut around a little with the knife,

[DELETED FOR CONTENT] with the pipe, then again with the candlestick.

Break a few bones with the wrench then when they lose conscientiousness end it with the revolver.
 
Candlestick; with it, you can properly 'get medieval' on their ass.

Though a mace would be preferable...
 
I'd probably stab the person a few times using the investigating Detective as a blade, and then Bludgeon him to death with Asmo's pride. I mean... I need something heavy to make sure I crack the skull enough times.