Both will also be in action against the Ospreys on Friday in a match that will go some way to deciding who takes the fourth place in the RaboDirect PRO12 play-offs.
And Townsend admits having both Weir and Dunbar back at his disposal and firing on all cylinders is a huge boost.
"They were in a huge tournament that requires a lot of effort, but I thought Duncan and Alex both played really well," said Townsend.
"It was an important win for us, but the second-half wasn't as fluent as we would have liked.
"When you have a defeat, you just want to play as soon as possible.
"We had to balance that need for them with their physical and mental state."
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