Basically how much price reacts to that level. A weak wall might be one with only the minimum mm/cluster requirement, and price reverses off of it maybe once or twice. A strong wall might be one where there is always a strong reaction when price gets near it, and more “bricks” keep getting added to it (i.e. more clusters and mm’s get created when price returns to that level)
There is no way to know in advance when a price level should no longer be considered a wall. (Keep in mind though that just because price breaks through a wall level, this does not mean it is no longer considered a wall.)
