Swim observation from this weeks training

So I made an observation this week after my pool sessions. I have noticed that each time I get out of the pool I have zero fatigue in my legs. My kick really isn't that strong, I use it mostly for balance and I have been doing the TI drills before each swim, which has helped alot. Now my arms, lats, shoulders and other back muscles, different story! Those are seriously fatigued at the end of a swim. They are actually even sore most times and stay that way for a good part of the day.

Now I am not sure if this a good thing or a bad thing. I would guess coming out of the swim with really fresh legs is a great thing for tris, but is something wrong with using mostly the upper body for the swim?

Since changing to breathing on every stroke I am no longer having any breathing issues and really the only thing that I feel is keeping me from swimming longer is just general swim conditioning. Things seem to finally be coming around for me and it is amazing what you can do if you actually give it an honest attempt. I was able to swim 2x200yds today for the first time ever! Not a long distance, but I did feel like I could have done one more set, but I didn't want to push it to much.