Bandora was planning on targetting Goushi the whole time. Barza explains how Shigeru (a Japanese boy) was kidnapped because it's his 10th Birthday and there was a full moon that night and she needed all of that including the boy in order to create a powerful Sword that would eventually belong to the Knight monster, as shown here in regular size and as shown here in Giant size
Power Rangers wound up using footage of Goushi against Dora Knight when Rita was explaning how she had used the monster on Tarmac 3 which is shown here
The blue that covered the Knight's Sword, as shown here in ZyuRanger footage, that blue was actually a protection method because Shigeru had assisted in making the Sword which means the Sword couldn't hurt him because the Sword can't hurt its maker.
There's a scene in which the Mecha in ZyuRanger fires an eye beam and transports Shigeru into the cockpit in order to take advantage of the Sword's weakness however Power Rangers did something a little different with the footage which you can see in the following 2 images:
The shot to the left is from ZyuRanger, the shot on the right is from Power Rangers however the shot in Power Rangers is still ZyuRanger footage. Here's what they did. They edited the beams from yellow to blue and in the shot I'm showing here, they ended up removing the kid from the shot as well. They made it so that the beam was what caused the Knight's Sword to turn blue.