It was one of those bits that may have “looked good on paper,” as the old cliche goes, but in actual execution, it was a different story.

At least, that’s our opinion of the “duel” fought between “Late Night” host Jimmy Fallon and guest Nathan Fillion, the charismatic leading man of ABC’s “Castle,” Friday night on NBC.

You can form your own opinion of this “duel” — waged with elaborate protective, plexiglass armor and suction-cup “arrows” — by watching the clip, above. For us, though, the interview segments between Fallon and Fillion were much more engaging.

In Part 1, Fillion, 41, reminisced about his days as a young actor in New York, where he starred on “One Life to Live.” He also gave instructions on how to comport oneself on a celebrity red carpet, advice we hope might come in handy someday.

In Part 2, Fillion shed some light on his private life in L.A., telling Jimmy a yarn about a backyard barbecue he held in which he accidentally served veggie burgers dripping with pork fat to some vegetarian guests.

He also teased the upcoming season finale of “Castle” — airing Monday (May 7) at 10/9c on ABC. The big question on this show always seems to center on the sexual chemistry between its two leading characters — Richard Castle (Fillion) and Det. Kate Beckett (Stana Katic). Fillion was careful enough not to reveal what happens between these two as the season comes to a close.