Weapontake

The weapontake was set for the morrow. When all is ordered we will Set out. (Theoden, in LR v. iii)

The word wapentake (OED: 'a subdivision of certain English shires, corresponding to the "hundred" of other counties') is well known in the context of English history, but not in the sense in which Tolkien uses it. It derives from the Old Norse vapnatak, and clearly consists of the two components - weapon and take; the corresponding word in Icelandic was used to mean (among other things) the taking up once more of weapons which had been laid aside by those attending the Althing (the Icelandic parliament). The route by which this word came in English to mean an administrative region rather than an event can only be guessed at; the OED entry offers some ideas. Tolkien decided to take the word at face value, and thereby assign to it (or rather to the respelt form weapontake} an obvious meaning which he needed for his narrative.

The Ring of Words (OUP 2006)