To "stanch" (also spelled as staunch) means to stop the flow of something, typically blood from a wound, thereby putting an end to it.

১. To reinforce means to strengthen, whereas stanch specifically means to halt or stop.
২. Being weak is a state of vulnerability, quite the opposite of the active verb stanch.
৩. Smooth out refers to leveling a surface, which is not relevant to stopping a flow.

অতিরিক্ত তথ্য: চিকিৎসাবিজ্ঞানে রক্তক্ষরণ বন্ধ করাকে ‘stanching the wound’ বলা হয়।