'Weaker' in the Bible

There was a long war between the house of Saul and the house of David; but David grew steadily stronger, while the house of Saul grew weaker and weaker [to the point of being powerless].

One man’s faith permits him to eat everything, while the weak believer eats only vegetables [to avoid eating ritually unclean meat or something previously considered unclean].

In the same way, you husbands, live with your wives in an understanding way [with great gentleness and tact, and with an intelligent regard for the marriage relationship], as with someone physically weaker, since she is a woman. Show her honor and respect as a fellow heir of the grace of life, so that your prayers will not be hindered or ineffective.