your english is incomprehensible dude. there is no clear and explained thought in your posts. you also have everything in one long sentence. you go from talking about a hud, to collision, then randomly to damage.
if you only want the widget for the pickup to show when the player overlaps the weapon then just script it that way. on begin overlap → create widget → add to viewport. on end overlap-> remove from parent. you will also want to check the overlapping actor to make sure its a player.
as for the damage theres many ways to accomplish that part. you could have a script in the level bp for example that gets all actors not overlapping the safe zone and apply damage at a regular interval.