Note that UBWS will allow you to use the weapon specials, if the real weapon skill you actually possess and Tactics are both high enough for that level special.
Mage Weapon DOES NOT.
I personally run a PvM hybrid mage template that has 80 Chivalry and GM tactics.
Note that only an idiot runs tactics (if their template uses it) at a total under GM, for the simple fact that there is an additional DI bonus for GM (real points or not), so that the "ideal" amount of tactics is 90 real +10 from somewhere else, for a true weapon-skill user. Someone running a template like mine wouldn't be limited to the "real" component, as ALL it does is DI, and would probably be better served havign anatomy instead of tactics (lower DI, but helps the EI/Anatomy defensive bonus for mages when not using a weapon).
I am PvM only, and only use the weapons for defense and for supplementing damage (monsters that dispel can quickly cause you to do a full mana dump, maintaining your summons). I found I do much better using a SCMW bow, even with a -1 FC, with my summons, than casting summons and then mana dumping spells onto big targets (like champ bosses, peerless, etc.) In fact, I was INCAPABLE of getting looting rights, even wearing an SDI suit, of getting peerless looting rights with my mage until I added the bow (And its support skills). With the Bow, I can cast summons more often, heal/cure party members and their pets, and STILL keep up a good DPS rate (better, actually) without having mana issues - all while getting looting rights that would not come when I tried playing a more pure mage template. For that matter, if the bow has Hit Mana Leech, it effectively doubles my mana regen (don't laugh; even getting back 2-3 mana a hit adds up when your suit is 40% LMC)