In any shelter, weapons can be used as a means of control or chaos - not something you want when there is any risk of a family member turning sideways mentally, or when one member is already abusive. The less potential for violence inside the shelter, the better the odds of surviving the full period necessary. The bigger threat, once the doors are sealed, might be from within, not from without. That's why you might want to consider carefully what, if any weaponry you decide to stock, who's going to have access to them and under what circumstances, and how well you and they will be trained in using them. If you have any doubts that they can and will be used safely, and if you want any smaller family members to feel secure mentally, focus more on preventing the need to defend (more secure shelter doors, tamper-proofing ventilation systems and waste-disposal systems, keeping boredom and anxiety to a minimum by including comfort items and activity materials/equipment), and less on stockpiling weaponry and ammo.

In a genuine nuclear attack, anyone out in the open during the first two days minimum is not going to be a threat for long; ARS will set in quickly and any shelter with less than a protection factor of 100 will only delay the inevitable. Gas masks are not going to help much if your clothing or gear can't withstand the full brunt of fallout radiation or make it through even the seven-hour decay period. Those taking a risk outside after 48 hours, but before the 2-week period recommended, will need either to keep their outside activities short and quick, or risk accumulating lethal doses. Their strategy will be to get in and out as quickly as possible, and not to stick around if there's any hint of resistance or pushback. Keep in mind that all of the radiation figures will vary greatly depending on the microenvironment - while a hilltop might register a lower reading, readings in the valleys below might be far higher due to gravity and greater accumulation and concentration of fallout.

Considering the construction of the shelter and its location, any "marauders" making the rounds after two weeks may find it exceedingly difficult to get inside the shelter itself and, depending on how desperate they are and how likely official law-enforcement or military parties are to discover them beforehand, most will simply move on to less secure sources of food, etc. rather than risk being caught out and, under emergency powers to the governments left in charge, being summarily shot as looters. This is why a radio can be extremely important - official reports may give warnings of attackers in the area and provide instructions for residents on when it may be safe to emerge.

While a nuclear exchange may seem like TEOTWAWKI, it's not how governments view it and it's not how most citizens would likely view it. The instinct is for self-preservation and, beyond that, the return of some semblance of normalcy. If there is a government left (even if under martial law), their primary role in such a scenario is to maintain order and provide relief wherever and however possible. If one is inclined to think that nobody's coming to help, it is preferable to have established community networks or mutual-help networks in order to fill that void.