1 - People who hates Putin regime still hates them, maybe a bit more, not much to gain here;
2 - People who likes Putin will hate you, again not much to lose here;
3 - People in the middle might hate Putin, but will definitely hate you more because you DIRECTLY hit them;
4 - Sending javelins/stingers to Ukraine will NOT stop Russian troops, but only to inflict more damage to them and at the same time make siege much more bloodier. It will just prolong the conflict with net lose on ordinary Ukraine citizen's side. Ukraine is still going to lose (and at the same time lost more human lives) anyway. The fantasy of "ordinary citizen taking urban guerilla warfare and driving enemies out" only works in games, unfortunately.
5 - If western countries REALLY want to minimize the damage to ordinary citizens, there are two feasible ways, one is to send in peace keeping troops including Air force and play a strong face to Putin. To avoid conflict with advancing Russian army a no-fly zone can be setup in Western Ukraine to accept refugees. The second way is to push the Ukraine army to let ordinary people to flee, not to keep them in the city.