Giroud opened the scoring before helping lay on goals for Aaron Ramsey and Mathieu Flamini in the 3-0 win at the Emirates Stadium.
His impressive display came shortly after a poor showing against Monaco in the UEFA Champions League, with Danny Welbeck then preferred up front for the FA Cup win at Manchester United.
Asked about Giroud's mentality, Wenger responded: "It's one of his strengths.
"This is a boy who played at 22 or 23 years old in division three and then becomes an international player.
"You need some mental strengths to do that because there is no red carpet and you have to work hard.
"You need some special strengths - Giroud had an outstanding game today.
"I know all these offensive players have the quality to deliver something special but what is for sure is they understand each other better than six or seven months ago.
"That makes everybody more dangerous."
The scoreline flattered Arsenal somewhat, as they were made to work hard by West Ham right up until Ramsey's second goal nine minutes from time.
"We controlled the game in the first half, created many chances, but couldn't score," Wenger added.
"In the second half we had a weaker moment coming out of the dressing room, I felt we were a bit short on energy for a while and West Ham were on top.
"In the final part of the game we looked dangerous of capable but we had to be patient and organised, overall we scored collective goals like we love to play."