Bony has 19 goals to his name in all competitions this season and has put in a string of impressive performances up front for Garry Monk's side of late.
Having been without Michu for much of the season due to an ankle problem, the Ivorian's goals have helped secure a win over rivals Cardiff City, while his work-rate was in evidence as Swansea held Serie A high flyers Napoli to a goalless draw in the UEFA Europa League.
Williams claims Bony has been invaluable in recent weeks, telling the club's official website: "We had Michu's goals last season but he has been out for a while, and Bony has stepped up for us.
"I think confidence is a big thing, particularly for strikers and you can see the confidence he is playing with.
"We love him and he is involved in the build-up a lot more now. The main thing is confidence, and he's getting that from finishing his chances."
Bony will likely lead the line for Monk's side in the second leg of the Napoli tie at Stadio San Paolo on Thursday, with the Welsh side targeting a valuable away goal.
Even if he fails to find the net, Williams feels Bony's recent displays could lead to opportunities for team-mates.
"It is not just his goals, during the last few weeks I have really felt sorry for the opposition defenders as he has been unplayable," Williams added.
"He's got to be the strongest player in the league. But he uses his strength and body well.
"His strength is obvious, but his touch, his awareness has been excellent too. He is on fire at the moment."
