Eriksen scored his first goal for Brentford in the club's shock 4-1 win at Chelsea in the Premier League on Saturday.
The goal was Eriksen's third goal in as many games for club and country, having also struck twice during the recent international break for Denmark.
The 30-year-old suffered a cardiac arrest while playing for Denmark at EURO 2020 and had his heart fitted with an implantable cardioverter-defibrillator device which prevented him from playing for Inter Milan.
After his contract with the Italian champions was terminated, Eriksen joined Brentford on a six-month contract in January and has so far made four appearances.
"Christian is a top player, an unbelievable character and he brings quality and calmness to the team," Frank waxed lyrical on his player's performance.
"You can give it to Christian and he'll always find a solution.
"From the beginning I thought 'everything has been checked in his entire body'. He didn't have an injury like an ACL and when he took that decision that he wanted to play in the World Cup, that determination, 'I want to come back into football' [was there] and his foundation physically was quite good.
"We never knew how quick it would take to get to this level but it's impressive how quick."
Brentford's win at Stamford Bridge has taken them eleven points clear of the relegation places.
