While best known for their Renaissance-era dress uniforms -- brightly striped puffy-sleeved shirts and pants -- along with their ceremonial battle axes, they are a formidable modern security detail, according to Widmer, who now runs the entrepreneurship program at the School of Business and Economics at the Catholic University of America.
Widmer had a kinship with Benedict in the late 1980s while he was a young German-speaking member of the guard and Benedict, whose native tongue is German, was a top cardinal serving John Paul II.
He described Benedict as an "unbelievable introvert." He said Benedict was always friendly with people at the Vatican one on one, even beggars on the streets, but large crowds sapped his energy.
The task of protecting two popes would have meant doubling the Swiss Guard force, a group unaffiliated with other Swiss security forces, as the guard predates the Swiss state.
But Widmer suspects that would not have been an issue anyway. His hunch is that Benedict will retire and remain cloistered.
"My guess is Benedict is not going to leave the Vatican," Widmer said. "It's not like he's going to make these huge moves. My guess is anything he's going to write and say will only come out after he dies."
A turbulent time
Before he became pope at the age of 78 Benedict had talked at length about retiring.
Speculation has swirled over what finally pushed him to step aside -- Vatileaks, the sexual abuse crisis, or the growing tide of secularism.
The "Vatileaks" scandal began with his butler leaking documents showing disarray and mismanagement and led to an internal review that was reported to contain details of gay sex scandals (reports which the Vatican calls baseless) and money woes came to a close this week when three cardinals reported their finds back to the pontiff.
The Vatican spokesman said the matter was concluded and the pope would reveal the contents of the report only to his successor.
The sexual abuse scandal continues to haunt the church as reforms have slowly taken hold across the American church and other cases have surfaced around the globe.
While the vast majority of the abuse cases happened in the 1960s, '70s, and '80s, the recent revelation of more case and the failings of the church in dealing with many of them have left fresh scars that have been slow to heal, victims' advocates say.
Cases are still in the process of being litigated. Two top American cardinals were deposed shortly before they were to leave for Rome for the pope's farewell.
Benedict was unable to stop the tide of growing secularism in Europe and the United States, though he often railed against it.
All of it likely took its toll on the 85-year-old who walks with a cane, has a pacemaker, and has looked frailer and frailer in recent months. But in the end it was his strength that failed him.
In retirement he will have none of those global problems to sort out anymore. Those responsibilities will fall to the next pope.
Instead, Benedict has said his task will be prayer and reflection.
Sister Armijo cried when she found out the pope was resigning. But now that she has had time to process the idea, she said her feelings have shifted from sadness to gratitude.
"He's a person of great courage to do something like this. To dedicate his life to prayer. I think it will help people to see there's a value to dedicating your life to prayer," she said.