Unless there's another model, it'll be quite confusing...
Since not many people use this, to make it usable on horseback, Hp has to be reduced to 400-420. That'll make it a low armor variant with stats between a kite shield + norman shield with good speed.
I've barely seen a Triangle Shield on NA, and it seems like the Byzantium folks on EU would mostly prefer this be a cavalry shield, so your proposed change would probably be well-received.
How difficult would it be to add a new shield with the current Triangle Shield's stats/model but Heraldic? Call it Heraldic Triangle Shield or something. There is a dearth of fast 2-slot shields, so most dedicated shielders still use the fast 1-slot shields even though they have spare slots.
EDIT: Similarly, what about adding 2-slot versions of the ECS and Knightly shields that use the same models as their 1-slot versions but with roughly the same stat modifications as Heater->Heavy Heater? i.e. +1kg, -3 speed, +5 armor, +25% HP? I equip a Heavy Crossbow sometimes because I figure "why not, I have the slots", but better 2-slot shields might entice me to forego the crossbow. 1h+shield+xbow seems to be the whine of the month, but most of us only do it because we don't have anything better to use our slots on.
