Pacific Rim: Gipsy Danger's Sword

Everyone knows that Pacific Rim was a bit over the top. Less plot-driven than it was giant-freaking-robot driven, the film is a bit more spectacle than substance. Still, that spectacle was something to behold, and Guillermo del Toro certainly delivered on how awesome a giant robot movie could look. Compared to, say, Transformers.

When examining the film, many viewers noted a number of plot holes, not the least of which was Gipsy's sword arm which wasn't utilized until near the end of the film. It seems like a major oversight that the operators of the Earth-saving robot would forget they had the sword until the climactic battle required a plot-saving device.
I however think that it's not as big a plot hole as people think it is. Mind you, it is a plot hole, but I thought of an explanation that makes it a smaller one. If the sword was an addition to Gipsy after it was moved to Hong Kong, and was part of repairs/upgrades that might have been done while preparing the older robot for fighting, then the sword would have not been there in the first half of the film and also, Charlie Hunnam's character wouldn't have known to use it.
Just a thought I had, not that it was at all hinted at in the movie or that it fixes any of the other ridiculousness the movie had. Just a thought.