Bardolph steals money from a church, and Pistol reports the crime, whereby Bardolph and Nym are executed.
So, Nym stole from a church and paid the ultimate price.
I've never heard the word "nym" used in this context before but I like it. It's different from the one that BD found:
A nym (pronounced NIHM and a shortened form of "pseudonym,") is a name invented by or provided for an Internet user in order to conceal the user's real identity and, in some cases, to expressly create a new and separate Internet identity.
And for completeness, from the American Heritage Dictionary entry for pseudonym:
NOUN: A fictitious name, especially a pen name.
ETYMOLOGY: French pseudonyme, from Greek pseudōnumon, neuter of pseudōnumos, falsely named : pseudēs, false; see pseudo– + onuma, name; see n-men- in Appendix I.