When we are young we wrap ourselves in mail and plate to ward of any blow severe enough to cause major contusion, invalidity, or mortality. A we age our strength depletes and by necessarily the weight of armor must lesson despite the weakening flesh and bones need for more sturdy protection. As with the elderly Don Quixotes sheathing eventually the joints cease to function as they should, the dented sections begin to outnumber the remaining pristine steel, the chain becomes tattered and unbecoming for the knightly figure, more pastiche than protecting.
The onset of fragility is a matter of certainly, the warrior must eventually put aside the lance for less sturdy implements, perhaps the pen or even heavens forbid the walking cane.
Consider if you will the stalagmite, a wonderous firm structure, imperial, upstanding, seemingly immovable. Contrive this mighty spear of ice to suffer the rigors of time, changes in conditions and environment and that same firm pike will become progressively frail, sufficient to shatter into a thousand shards at an inopportune touch.