However, the Bridgend-born player again played a key role in Wales' second Grand Slam in four years before his injury misfortune struck again.
"It's just a matter now of a run of games to get him back up to speed," Holley added.
"He's coped with it (the injury) with a real level of maturity this time, he's come back right and it could be a big season for him.
"It's always important to have those 'X-factor' guys in your team.
"No disrespect to anyone in our squad but people like Gav and Shane (Williams), they do have a bit of magic and can create something out of nothing.
"We had a particularly good forward effort over in Leinster last weekend (the Ospreys losing 19-13), scores were few and far between but we made some line breaks that we were unable to finish off."
Walker powering through season
As well as having Henson available again Holley can also call on Williams after injury to add to strength on the wings against Ulster.
Tommy Bowe could face his former side while Scotland wing Nikki Walker scored a fine try in Dublin last week.
Walker for one is looking forward to Henson returning to boost his scoring chances.
"It's awesome to play outside him (Henson), he creates things and makes it so much easier for you," Walker said.
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