I don't know. After she retreated, I couldn't really fight any further regardless. [ Which he realizes Gilbert will understand with no problem, but since it actualyl feels relevant here, he elaborates for Undyne: ] I'm fairly certain I was going to die this week regardless. She accelerated the process somewhat, but not by much.

[ But that's not the important part here, and he's really only elaborating solely because it could be a bit confusing otherwise for the sake of talking about her capabilities. Break waves a hand dismissively as if to signify that this isn't the part he wants to focus on. ]

I don't think she had a barrier, but I wouldn't take that as a certainty. Dumpy actually came with us, and he managed to shoot her. It didn't take full effect as it did with Bill, but it was enough to slow her so that I could catch her. So your problem is combating that trick of hers for moving about quickly. Without something like whatever Dumpy shoots, an explosive would be useless. Fighting her hand to hand would be more effective.