I can teach you how not to get hit in the face, and still maintain control of the arm you want to armbar 
Try this: Place both your feet in his hips, with your knees well bent.
When he tries to hit you next, use your forearm to block him near the elbow, and then come over top and track your hand down his forearm to grab his wrist. Keep hold of that wrist and then press your shin out and down. Your shin should be in his elbow joint and pressing against their bicep, kinda like you’re trying to put your knee down.
He may try to hit you with the other hand, in which case, repeat the procedure on the other side.
If he concentrates on freeing his trapped arm, attack his other arm with your shin and hand–I find that if I push on their bicep near the elbow and slip it over my knee, then track down the outside of their forearm to the wrist, it’s easiest.
You should now be in this position–both feet in hips, his arms outside your shin, with your shins in his arms, pressing out and down, while you have hold of his wrists.
What you have to do next will take some getting used to, but does work.
Hip up. Use your feet on his hips to facilitate this. Remember–you want to hip UP, not push him away!
I’m going to describe the next as though you were armbarring his right arm. You’re going to do something very similar to the first armbar from the guard you probably ever learned 
Now, bring your hips down. On the way back down pull his right arm across your body, towards your right shoulder HARD to break his posture, and trap his elbow and arm with your hip and thigh. Press your knee in hard (but not at the expense of your hip and thigh pressure. This should help control both his posture and his shoulder so he can’t back out. You need his elbow at your hip at least, but the ****her the better. Don’t let go of that wrist. If you don’t make it to this position, probably a good idea to start over, or try something else.
There are two ways I find most useful to finish:
For the first, keep the grips you have, and rotate your body to the right, so your head goes towards his left knee. As you rotate, you have to slide your right leg off his bicep and across his body so that your shin is in his stomach and your foot hooks the right side of his body. Otherwise, your own shin will get in the way. Maintain your hip pressure on his arm throughout. Put your left leg over his face and hip into his elbow to finish.
–In reality, you may need to grab his knee with your right hand to help bring you around. You can also use this to sweep him to his back, if you can.
–Once you are around, you may need to pull on his arm with both of yours to finish, or do it sooner to keep his arm there. You know how that goes.
The other finish is to slip your right leg under his arm, then kick your right heel to his neck, pivoting your body perpendicular to him while pressuring down with your right calf to keep his posture down and keep him from backing out. Put your left leg over his face to finish. That’s pretty much the “standard,” arm bar from the guard. As before, don’t let up on your hip pressure and adjust your grips as needed to accomplish the desired end.
Making sense? I prefer the second finish as I personally find it affords me a better way to keep his posture down. The shin on the belly one, however, allows me to sweep him over a bit easier. Personal preference 
The best part about this hip up set up is that if you take a leg out and put it over his shoulder, you can triangle him just as easily.