"A Ranger never lets go of his weapon"

I found that scene to be symbolic, especially with the “never let go of his weapon” line.

His duty as a ranger means he has to pretty much fight every day of his life. Never letting go of his weapon doesn’t just literally mean letting go of the weapon, but also the burden you bare as a Ranger. For as long as evil remains, a Ranger must never let go of his weapon, the power and means to fight the evil off.

When he and the others finally defeated the Armada, he plants the sword down because his time’s done. He finally vanquished the evil he had been selected to fight. In other words, he lets go of his burden.

Some of the Rangers (and Kamen Riders/Super Sentai) don’t lose their powers by the end, but rather willingly part with them. In that same way, they let go of their weapon, knowing the battle’s over. Yes, their battles still continue in crossovers, but the burden is passed off to the next generation.