the sense that the character is now pathetic compared to his/her comrades
A number of factors have gone into getting us into this situation.
There's "bonus inflation". There simply
were not any +4 or +5 items in the original set. A pretty obvious point is that a magic weapon (or one favored in Weapon Mastery or the like) makes a figure
different from another of its level; counting on something so individually frangible to make characters
equal is an intrinsically poor design.
That very design on the part of players is a more basic problem, one that successive designers have addressed by accommodation. It is fundamentally at odds with the original D&D concept, which was designed to produce
inequality in outcomes as dictated by luck and skill. I can only wonder how people otherwise make sense of (much less rationalize keeping track of) experience points.
There are quite sensible reasons to undertake such a game, but the enterprise of replacing D&D with a more suitable rules set took big steps forward with 4e because of the designers' readiness to get rid of "sacred cows". Neither level drain nor treasure-destroying rust monster -- nor even death, except as temporary inconvenience -- seems to serve a purpose, because
the purposes have changed.
Maybe with 5e, we'll see magic swords, etc., removed at least from the category of +x bonuses (as those are essentially entitlements and parts of "character concept" and a scheme of
balance now). Versatility in ways to do things is more popularly risked, I think, than raw fighting power. Either as an alternative or in conjunction, there could be rules to ensure that treasures are not lost (unless perhaps suitable replacements turn up in timely fashion).
As 3e and 4e have already shown, one can give the "level drainers" less distressing powers. The "nerfed" rust monster seems just too silly to me, but YMMV. Eventually, people who find death by misfortune unacceptable must simply take death
out of the realm of fortune. However things average out, expecting the "unexpected" to manifest randomly is the point of rolling dice!