The Portcullis, is a very sneaky weapon. Armies charging at your door, you wait, and wait, and wait, and just when they think they're getting in, you drop it on them. They are stabbed, crushed, dead, and the men behind them can't get to you.
Archers would also shoot through the holes in the Portcullis giving them something to stand behind while still having enough room to shoot the arrow through.
*Disclaimer: I have done extensive research on each of these weapons. I am aware that there are many different versions of each of these weapons. I am not trying to spread false information. If you know and can prove any information wrong, please let me know and I will fix my errors. I have at least three references for all research on the weapons I will discuss through the challenge.