This is only with regards to ethical / non-violent interaction with others.
My defence is my ability to not be affected by the actions of others... tolerance and patience, basically. I can imagine it as, and take inspiration from, watching a good defensive boxer like Floyd Mayweather Jnr... ducking, weaving, moving etc. as anger, hatred, frustration etc. comes in like blows. Also, that slow motion imagery of Neo in The Matrix calmly observing and moving aside bullets / fists / kicks lends itself well.
The transition from defence to attack is forgiveness. That is, the letting go of any trace elements of upset I may have experienced from their attack - landed blows, if you will. This is important, just as in a martial art, you don't want to attack from a weak and vulnerable position. So much better to steady yourself, get your senses, and then attack yourself.
Attack in this sense is to love. My defence has minimised the blows of anger and hatred on me, and forgiveness has allowed me to clear away any residual upset, and so now I am in a position to love my attacker. Just as it takes great skill to duck and weave incoming blows to minimise harm, it takes great skill to land your own blows... to love your attacker in an appropriate way that is actually effective. This first requires empathy... an understanding of what this individual before me needs. The second thing is compassion... a desire to relieve their suffering, some of which has led them to attack me. Just as in martial arts, picking the correct shot is difficult, and frequently will miss, and sometimes will even make me vulnerable to further attack.
The aim, of course, is to first pacify the individual, to then position my will to wish to help not harm my attacker, and to then find a way to help them. It's difficult and, just like combat in martial arts, the situation is fluid and dynamic. Like a great martial artist you have to be able to adapt very quickly. Technique is very important and must be honed. Plans are very helpful for beginners as they provide a rough structure to these interactions that can be successful for the most part... or that at least minimise any harm we might do.
Defence is the foundation. I have spent years and years practicing tolerance and patience because nothing pained me more than to hurt others. Forgiveness is also something that I have managed to master at a basic level of need (I can't comment on how I'd feel and react if someone murdered my mother, for example). Helping people is something I am very much at work on. It's usually enough to be able to pacify a situation... to respond without anger, to have no residual hostility, and to attempt with sincerity to understand the attackers position. This is enough, and if we all managed this then our world would be peaceful. Actually being able to help the attacker is like landing the knock-out blow... difficult! As with most knock out blows they come by surprise and are somewhat of a fluke. After all, human beings are too complex for us to truly know what it is we can do or be to help them. So when we do, it is usually quite fortunate. For those more attuned to higher states of consciousness then help can be inspired at an intuitive level... something that transcends our ability to rationalise and calculate, but that is usually uncannily precise and effective.
I find considering my dharma / ethical interaction practice as like a martial art makes it enjoyable and easier to engage with, in the same way I expect a martial artist enjoys studying, practicing and mastering their techniques. For one thing, it takes the personal out of it. It is just an interaction that can be stripped down to bare components and engaged with as a matter of form and technique, without the personal or the emotional becoming involved. It's really good fun for me, and it works very well.