Established in 1506 the Swiss Guard are one of the oldest continuously operating military units. But today they act as the ceremonial protectors of the Vatican.
They do have modern firearms in their arsenal but compared to their halberds Sig 550s and P220s don’t seem that odd.
The halberd is among the most versatile melee weapons. It allows it’s user to defend against charging calvary, deal with the armor of opponents, or attack melee combatants without entering the effective range of their weapons.
I suppose there is a slight difference that the Queen’s Guard still carry modern L85s even in their ceremonial uniforms.
The Swiss Guard carrying halberds are much more ceremonial to me. We know they have modern people out of sight with more proper equipment.