- Weapon type effect: you need more alertness to notice someone trying to kill you with a knife than with a halberd. There should be a chance to kill with one knife blow, rogue style, an inactive character at an unguarded area.
Holy crap, that's a good one!

That's a very good one! Finally something that gives a meaning to making small weapons!
(Insert an appropriate "you win a prize" picture here.)
We could combine that with the defending of others. Just integrate a little "defend this person" checkbox. For your own character this would be set on yes as a default.
I see one problem, if the button was along with the character description, and someone did something to make your character mad then left, you would prolly want to stop defending them, but couldn't because they're not in your location anymore.
I think if you are attacked your allertness should go up to 100% no matter what you are doing for several days, and seeing someone get attacked will also escilate it.
Good point. I was thinking about that but apparently didn't write it down. Though if your alertness goes up to 100%, you should at least temporarily stop working on your project, since that makes you jumpy and can't concentrate.
A similar effect would also be gained through loud noise, such as blowing a giant horn or hitting a cong. Everyone would have their heart jump to the throat and couldn't concentrate on their projects for a while, but if someone was trying to signal that an army of pirates is approaching, they'd be sure to have gotten everyone's attention.