MMH5.5 - Heroes of Might and Magic 5.5

"Armor spikes" perk says it will give +1/+1 now and another +1/+1 at level 20. This means that even if you pick the skill at level 7, the skill will be automatically upgraded at level 20; there is no need to wait until the hero becomes level 20+ to get it.

"Combat" skill for might heroes is a bit like "Sorcery" for mages; a great portion of its usefulness kicks in the middle and late phase of the game because of synergies between units and stats.

I understand, but there's no point in enduring a weak skill until level 20 just for it to become only normal (not strong) after level 20.
The word "synergy" can justify any numbers, so I usually look at the numbers first. The bonus is small (7.5%), and it's also rare/situational, only for retaliatory attacks. And if I'm going to sit and endure it for retaliatory attacks (where the main damage will be dealt by them + ranged attacks), then it won't synergize with "Readiness," which is in a completely different branch, incompatible with +1/+1.

In general, the limitation you've set – "skills with +2" – greatly hinders the game, in my opinion. Because even in the original game, +2 was a below-average bonus; normally, in-demand skills were valued at +2-3, and the best ones at 4 and higher. In your game, the strength of characteristics is reduced by 1.5 times (from 5% to 3.33%). That is, you are essentially leveling the skills to the level of +1.33 (if calculated in the original 5% characteristics). This makes it very difficult to balance skills at such a low level. For example, the same skill with +1 speed is valued at 4-5 of the original parameter (in Random Tactical Arena), i.e., at +6, translating to your 3.33% characteristics. And many other skills are also many times stronger than +2. For example, Empowered Spells.

What I will try to level up in your game are only fundamental skills that give a good bonus, and the skills leading to them. And all sorts of "+2 to a parameter" will only be taken as a last resort if nothing better is offered. With the exception of witchcraft and knowledge in the early game, which have not yet become devalued as in the late game.
Even an enhanced skill up to +2/+2 is unlikely to be leveled up; instead, I will focus on "Readiness" in this skill (if it is really as good as you say), or strong hero attacks. Neither of these is enhanced by +2/+2. Therefore, it would be best if such a skill didn't exist at all, as it would make it easier to level up other skills in this branch.