Dave Eichelberger birdied the 18th to finish alone in second at 7-under-par 136, while first-round leader and Monday qualifier James Mason was one shot further back at 6-under-par 138.
Sigel earned his first win since 1998 at last week's Farmers Charity Classic. This week he has put himself in contention to make it two in a row.
'Before last week, I wondered whether I'd win again,' said Sigel. 'Last week's win was very special.'
Sigel began the day three shots behind the overnight leader Mason. He coasted at even par until his first birdie of the day at the fifth to move to minus 5. Meanwhile, Bland was putting together an early charge at the lead under windy conditions at Upper Montclair Country Club.
Bland was two shots back to start the round but quickly picked up ground with a birdie at the first. He took the outright lead with back-to-back birdies from the third while Mason ran into trouble with a bogey at the opening hole.
'I got off to a good start and then the wind started swirling,' said Bland
At the eighth, Bland knocked a 6-iron within five feet of the cup to open a commanding three-shot lead over the rest of the field. However, Sigel came racing back. The 58-year-old put together a stretch of four consecutive birdies around the turn to match Bland at 9-under.
Bland regained the outright lead with a 25-foot birdie putt at the 12th before falling back into a tie after back-to-back bogeys from the 14th.
The 56-year-old South African's last victory on tour came at The Transamerica in 1996. That year Bland graced the winner's circle a total of four times.
Sigel played on par with Bland and closed out his round with two bogeys and a birdie over the final four holes for a round of 3-under 69.
'I'm pleased with my score,' said Sigel. 'I actually thought today's conditions were tougher than yesterday. Wind like this affects your swing.'
Bruce Summerhays had a bogey-free round of 4-under 68 to move into a tie for fifth at 5-under-par 139. He was joined by Jim Colbert and Dave Barr.
Butch Sheehan and Walter Morgan were one shot further back knotted at 4-under-par 140. Defending champion John Schroeder was seven shots off the pace at 1-under-par 143.
Full-field scores from the NFL Golf Classic