You're asking the right question, but I think you're maybe overthinking it a bit. The split between Blade and Blunt in Oblivion doesn't really force you into a build the way you're imagining — it's more just flavor than hard constraint.
Here's the thing: by level 12, you're still in the phase where weapon choice matters way less than your actual perks and gear. Both skills level at basically the same rate, and the damage difference between a sword and a mace at that level is negligible. If you're genuinely worried about "not committing," just pick whichever one matches your character concept and lean into it going forward. You won't brick your playthrough either way.
Where it does matter is late-game, but not in the way you'd think. The real difference is in the specific perks and enchantments available to each tree. Blunt gets some stuff that favors heavy armor and tanking (like the stagger bonuses), while Blade leans a bit more into speed and crit damage. Plus certain unique weapons are distributed between them — some iconic stuff is blade-only, some is blunt-only. So if you want a specific legendary weapon, that might matter.
But honestly? Don't stress it. Oblivion's skill system is forgiving enough that you can dabble in both and still be fine. Just stop using whichever one you like less and commit to the other. You've got plenty of levels left to specialize.
