Re: Ambassador class weapons
Nope - the E-C had a boxy structure there, with potentially one little pimple that could be interpreted as a point-emitter phaser. The model was then pulled apart, perhaps for storage, and reassembled differently for a DS9 appearance as USS Yamaguchi
of Wolf 359 fame, at which point an upside-down Excelsior
shuttlebay was glued under the fantail. A keen eye might spot this bay in a frame or two of DS9 "Emissary", but we don't really see the underside of the vessel in this episode so we can't tell whether there would be ventral phasers in other locations.
Some pictures and analysis here:
Well, the two structures I'm describing are visible on both the C model and the later modification used for the Zhukov and Yamaguchi. It's not very visible in "Yesterday's Enterprise," but is visible on the Zhukov in "Data's Day." You can see such a screencap on the Memory Alpha
page (second from top).
"If you think you're brave enough to walk the path of honor, then follow me into the dragon's den."