Bec de corbin is a short polearm, not a very good battle weapon. Similar to the way a LWA is not a great battle weapon. Except in NA for some reason where a lot of them use dinky short weapons. I have a clanmate who has a 15/27 build and sometimes plays with a bec de corbin, he 3 shots everything and does very well. On siege however, there is not a single polearm I would pick over the bec de corbin when it comes to effectivity.
34p never glances, it always does good damage, regardless of the armor your enemy has. Such high pierce damage allows you to do very early hits in the animations. 34p definitely does more damage on average than the 42c of the LWA, 50-70 body armour does a lot to reduce the effectivity of cut. The reason people do not use the bec on battle is the low length, and they don't use it on siege because they are all 2h scrubs and 2h is easier.
If it would in anyway reassure you I could play some siege with one and post e-peen screens
Little damage calculator test.
Bec with 5ps and 172 wpf
against 0 armor - damage: 50.2 - 55.7
against 25 armor - damage: 32.7 - 39.2
against 50 armor - damage: 15.7 - 30.2
against 75 armor - damage: 5.7 - 22.2
LWA with 5ps and 172 wpf
against 0 armor - damage: 61.3 - 68.2
against 25 armor - damage: 35.2 - 45.3
against 50 armor - damage: 15.2 - 32.3
against 75 armor - damage: 3.2 - 22.3
And I can assure you, that LWA is not glancing at all. Also it do more damage than bec, have shieldbreaking ability, little longer, faster and cheaper.
So, for what we trading lenght of this weapon? For raw damage? No. For armor piercing effectivity? No. For any special ability? No. For price? No. For speed? No. For slot economy? No.
Give bec's secondary mode fair 34 blunt damage and this will improve things a bit. Your formula for secondary mode damage (main damage-10) is not working here, because bec already has inferior raw damage output.
Again, it's situational, weapons were designed for specific purposes and the game reflects this (somewhat).
This weapon was designed for blunt damage, trips and heavy armor penetrating. In game this do not reflects at all. In this game 2H fantasy swords penetrate armor better than weapon that was designed for this purpose. (since miaodao and other 2H stuff have raw damage output even higher than LWA)