Ah right, the "opponent is trying to give up" trigger, forgot about that since I never use it. Well, if that is triggering at the same time as Last Stand then it looks like it's already in there. The problem you are seeing is likely due to the fact that the conditions for "very injured" and "opponent is trying to give up" are close to each other. If it is something like "very injured" is only 25% health left and "opponent is trying to give up" is around 10% left it is possible to score a hit that takes a glad from more than 25% to less than 10% and thus skip the very injured trigger.
Try setting up your #4 strat row to "opponent is trying to give up", and then have your #3 strat row be something like "I have less health than opponent" or some other health condition. This way if you are winning the fight your #4 trigger will fire allowing you to tank and get some protection from Last Stand and then if you start to lose before the match ends you'll switch to your #3 trigger and can start attacking again. I'm sure you get the idea, not sure if "I have less health than opponent" is the trigger to use or not, but you could even try the odd/even round triggers for row #3. Sometimes you'll get caught in the wrong round and your Last Stand trigger won't fire, but about 50% of the time you'll tank for their last stand and then go offensive the next round and then back to tanking and then back to attacking and so on. Those triggers were introduced when Nate wanted War glads to be more Tank n' Spank glads instead of the Total Parry fortresses they were.