A spire, currently, is best properly played as a long-range sniper ship that relies on kiting. Buff its speed and you make it too good at that (though there is usually counterplay to sniping as almost every map has cover, but this leads to uninteresting interactions, especially on more open maps).
Buffing its firepower is hard to do, and doing so is a risky proposition as, again, you make it better at what it already does well.
Buffing its survivability across the board seems to be the most reasonable option. The problem with this being, the Spire is basically a competitor with the Galleon in terms of a niche, and the Galleon will almost always outshoot the Spire thanks to its dual heavy weapons, not to mention it's far tankier.
By the way, unless the ship rebalance touched more than I remember, the Galleon is in fact faster than the Spire, at least in terms of top speed. It's obviously got horrible turn speed, but that's arguably not horribly important.
A slight but all-around buff could be wise; it could use a little more speed, a little more armor, and a lot more hull. Not much can be done with the guns, though making the top right weapon face forward could help it in terms of versatility.
Another idea I had was instead of modifying its stats, it could be given a top right forward facing light weapon, and a right facing gun next to it. This essentially "splits" the current top right weapon, and gives it a guaranteed two forward facing weapons, as well as side protection. I like this adjustment the best, because the Spire is supposed to be a glass cannon, and thus should offer the best firepower. It should rival the Galleon. Unfortunately, this is difficult to do without giving it a second heavy weapon, but, it's also possible to give it a second bottom light weapon to enable a potential, blistering four weapons on target assuming the pilot is unneeded (which is seldom the case, which would give this adjustment counterplay in the form of keeping the pilot busy).
Giving the Spire a couple more guns would not only reinforce its role as a glass cannon, it also affords it excellent versatility by sheer volume of weaponry. That'd do well to boost it up into competitive territory, don't you agree?