I saw a cartoon character(平沢唯, 「けいおん!」, ep.2) use this exclamation: 「無念なり」 expressing her regret at the lack of money. I'd like to find a grammar point explaining the use of 「なり」 here. After some lookup on the Internet it seems that なり can also be written as 成り (so I take it it's a derivative of 成る). However, it appears that none of the grammar books I've searched gives an explanation to this specific use (everything I've found concerns only V + なり and doesn't make much sense in this context). Any help will be appreciated!