[Initially he's not so surprised at all when Yamato seems to be for ignoring such an offer; usually, he's a very capable sword, with a good handle on whatever he's doing. (Or otherwise, good enough.) On the other hand, even that first step just doesn't look like an ideal way for him to walk on his own, so when Yamato's hand meets with his, he's happy to hold it back and take his step to catch up to the other, then a tentative few more to see if Yamato will follow.]

Then, I'll do my best to make sure you won't fall, Yasusada-kun! Feel free to use me to balance.

[And, a nod in the direction of the cashier they're taking slow steps towards.]

We should pay, and get a bag for your other clothes, don't you think?