Paul Lambert's side came into the weekend four points above the drop zone in the Premier League, but saw that gap reduced following a defeat in which Shelvey provided a moment of pure quality at the Liberty Stadium.
The midfielder capitalised on a poor Ron Vlaar attempted clearance to find the back of the net from the edge of the centre circle to put Swansea back in front, as the hosts recorded their first back-to-back league wins since December 2012 and eased any lingering fears of relegation.
Bony scored both goals in Swansea’s victory at Newcastle United last Saturday and wasted no time in adding to his goal tally seven days on.
But the winger was the architect for team-mate Agbonlahor's leveller, with his cross from the right allowing the striker to tap home in the 22nd minute for his first goal in 12 games - and his second against Swansea this season.
The visitors' joy was short-lived, though, as Shelvey’s sublime strike restored Swansea's lead four minutes later.
The midfielder knocked the ball down from Vlaar's bad attempt to clear, before beating Guzan with an audacious long-range right-foot strike - a sure-fire goal-of-the-season contender.
And things went from bad to worse for Villa in stoppage time, as substitute Emnes was felled in the box by Baker and Bony coolly slotted home in a carbon copy of Swansea’s winning goal at St James' Park last weekend.
