This is regarded as a bit of a myth. Search for swords in this official PDF https://www.parliament.uk/documents/commons-information-office/HoC-Chamber.pdf https

This is regarded as a bit of a myth. Search for swords in this official PDF https://www.parliament.uk/documents/commons-information-office/HoC-Chamber.pdf https://www.parliament.uk/documents/commons-information-offi.... MPs have never been able to carry weapons in to the chamber so if it was a rule it's a bit silly (which doesn't mean it's not true given how silly the rest of the UK democracy is).